diff --git a/CLAUDE.md b/CLAUDE.md
index ab75119..c03fb36 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -552,6 +552,131 @@ survived 92 commits and fourteen days in the public GitHub mirror, past five aud
 independent reviews, because every one of them read the code under change and this sat in a test
 nobody had reason to open. Fixtures are never live values; there is no case where they need to be.
 
+## Settings export/import
+
+`commands::settings_export_commands`, `storage::settings_crypto`, `models::settings_export`
+(triple-c#35). Exports the *host* environment — global `AppSettings` plus the global secrets that
+live in the OS keychain instead: the shared Claude Code OAuth login and the model gateway's two
+keys. Per-project settings, per-project secrets, and anything in a project's Docker volumes are
+deliberately out of scope — this is not a project backup.
+
+- **`AppSettings` is not entirely the non-secret shape it looks like, and a review of this feature
+  caught the one place that isn't.** `WebTerminalSettings::access_token` is a live bearer
+  credential for a server that binds every interface — exporting `AppSettings` wholesale would
+  have carried it along as if it were as inert as a port number, and importing it would have
+  applied `web_terminal.enabled` and the token together with no more warning than any other
+  setting, letting a crafted export silently stand up a LAN-listening terminal on the next launch.
+  `export_settings`/`apply_settings_import` carve this one field out into `ExportedSecrets`
+  instead, with the same "only overwrite what the import actually has" treatment as the other
+  three secrets — except "leave it alone" has to be done by hand in `apply_settings_import`, since
+  unlike the keychain secrets this one lives inside the `AppSettings` blob that gets replaced
+  wholesale. `SettingsImportPreview::enables_web_terminal` also exists because of this: `enabled`
+  and the token are independent fields, and "this turns on a listening service" must not hide
+  inside a generic "settings replaced" summary. Read this as the standing example of the class of
+  thing to keep checking for in this feature, not a one-off fixed bug — any other field that looks
+  like config but is actually a live credential would have the same problem.
+- **Encrypted because it can carry live credentials, not for appearance's sake.** Argon2id derives
+  a 256-bit key from the user's password (memory-hard — meaningfully resistant to GPU/ASIC
+  brute-forcing, unlike PBKDF2 at any reasonable iteration count), AES-256-GCM does the actual
+  encryption. A wrong password fails GCM's authentication tag rather than producing silent
+  garbage. The salt and nonce are not secret and are written in the clear in the file's own
+  header — the salt's job is only to make two exports of the same password derive different keys,
+  and the nonce's only requirement is per-encryption uniqueness, which a fresh random draw on
+  every export already gives it.
+- **The save/open dialogs are opened from Rust**, the same boundary `file_commands.rs`'s
+  `pick_save_path`/`pick_files_to_upload` draw and document at length: a frontend-driven dialog
+  handing Rust a host path string is the exact shape of bug that produced this app's past
+  criticals. `preview_settings_import` resolves the chosen path itself and remembers it
+  (`AppState::pending_settings_import`) so `apply_settings_import` re-reads the same file without
+  a path ever crossing back over IPC. It also pins a hash of the file's ciphertext next to that
+  path, and `apply_settings_import` refuses to proceed if the file on disk no longer matches it —
+  otherwise confirming a preview would not actually be binding on what gets applied, which matters
+  given this feature's own threat model: a file shared between people may sit in a synced or
+  otherwise shared directory that changes between the two calls.
+- **The decrypted payload is not cached between preview and apply — only the password is reused.**
+  The frontend holds the password in React state and passes it to both calls; nothing in Rust
+  holds decrypted plaintext — secrets included — in memory for longer than one command's
+  execution, so `apply_settings_import` always re-decrypts rather than reusing anything
+  `preview_settings_import` computed. `preview_settings_import` returns counts and presence flags
+  only (`SettingsImportPreview`), never a secret value, so it's safe to hand to the frontend and
+  render directly.
+- **Import replaces settings wholesale, but only writes secrets actually present in the file.**
+  An import is "restore this environment," so the settings half is a full replace, not a
+  field-by-field merge. Secrets are different on purpose: an absent secret in the export means
+  "the source machine never had this configured," not "delete this on import" — a user who wants
+  to clear a secret already has dedicated UI for that (signing out of shared auth, clearing the
+  gateway key). Secrets are restored *before* the settings replace runs, not after — replacing
+  settings is what triggers `reconcile_gateway`, and restoring the other way round leaves a real
+  window where a gateway recreation happens against the destination's old keys.
+- **A restored gateway secret nudges a running gateway container to recreate itself, even when
+  nothing about the gateway's *shape* changed.** `reconcile_gateway`'s `gateway_shape_changed` only
+  compares port/provider/base URL/models — deliberately, since that's what's rendered into the
+  container's config — so a secret-only change (same shape, new key) is invisible to it. Left
+  alone, a running container would keep serving the old key material indefinitely after an import
+  that restored a new one. `apply_settings_import` tracks whether either gateway secret was
+  actually written and, if the gateway is enabled and its container both exists and is running,
+  calls `docker::gateway::ensure_gateway_running` directly afterward — its own fingerprint already
+  includes the secret rotation id (`storage::secure::get_gateway_secret_version`), so it recreates
+  exactly when it should and no more.
+- **A keychain write failing during import is reported back, not only logged.** Each of the three
+  `secure::store_*` calls collects its error into `SettingsImportOutcome::secret_restore_warnings`
+  in addition to logging it — an import that silently restores two of three secrets but not the
+  third must not read as unqualified success just because the settings half of the import (which
+  runs after, and is validated before any of this) went through. `apply_settings_import` returns
+  `SettingsImportOutcome { settings, secret_restore_warnings }` rather than bare `AppSettings` for
+  this reason; `ImportSettingsModal` shows any warnings alongside the "Settings imported" message.
+- **The imported settings are validated *before* any secret is written, not just before the
+  settings replace.** `apply_settings_import` calls
+  `settings_commands::validate_settings_update(&current, &settings)` — the same checks
+  `update_settings` runs internally, pulled out into its own function specifically so this caller
+  can run them first — and only proceeds to the three keychain writes if that passes. A review
+  caught the earlier ordering: writing secrets first meant a rejected import (a bad env var name, a
+  disallowed host path) still left the keychain overwritten with the file's secrets while the
+  settings themselves stayed unchanged, a silently half-applied state the error message gave no
+  hint of.
+- **`read_and_decrypt` checks `format_version` before attempting to parse the full payload, not
+  after.** A version bump that isn't deserialize-compatible is exactly the case that check exists
+  for, and parsing the full struct first would fail on the shape mismatch before the version check
+  ever ran. Neither error path interpolates what `serde_json` actually says into the message
+  shown to the user — its type-mismatch errors quote the offending value inline, and the plaintext
+  here can hold a live credential.
+- **The 8-character password minimum is enforced in `export_settings` itself, not only in the
+  export modal.** The frontend minimum is a UX nudge; the Rust command is the actual boundary a
+  weak password has to cross, and Argon2id's memory-hardness buys little against an attacker who
+  can just try a short password directly. Measured with `.chars().count()` (Unicode scalar values)
+  rather than `.len()` (bytes), to stay as close as this pair of languages allows to the frontend's
+  `.length` check (UTF-16 code units) — the two only diverge on astral-plane characters. The
+  derived key and both plaintext buffers — the payload built for export, and whatever `decrypt`
+  recovers on import — are wrapped in `zeroize::Zeroizing` for the same reason every other secret
+  in this codebase gets handled carefully — cheap insurance (`zeroize` is already pulled in
+  transitively via `aes-gcm`) for material that exists only to hold or produce live credentials.
+- **The preview also discloses non-blank custom base URLs** (`global_ollama`, `global_llamacpp`,
+  `global_openai_compatible`, `gateway.api_base`) so an import that would redirect model traffic to
+  a different server is visible in the confirmation dialog rather than discovered later — these are
+  endpoints, not secrets, so `SettingsImportPreview` carries and `describeImport` renders the actual
+  URL rather than just a presence flag. `describeImportWarnings` additionally calls out a web
+  terminal token that arrives with the terminal left *off*: `start_web_terminal` only mints a fresh
+  token when none is already set, so a planted token would otherwise activate silently the next
+  time someone turns the terminal on, with no import-time signal that it wasn't freshly generated.
+- **The preview also discloses a custom Docker image, and warns on one every time — not just on
+  change.** `custom_image_name`/`image_source` weren't in scope for the base-URL disclosure above,
+  but a review pointed out they're a sharper version of the same problem: this is the image *every*
+  project container is created from (`models::container_config::resolve_image_name`), so a crafted
+  export pointing it at an attacker-controlled image is a path to running arbitrary code with
+  whatever a project's containers are allowed to reach, not merely a redirected API endpoint.
+  `describeImportWarnings` fires on `image_source == Custom` unconditionally rather than only when
+  it differs from the destination's current value, since re-importing the same risky configuration
+  is still worth surfacing every time a user confirms an import.
+- **Every free-form string a preview surfaces is sanitized and length-capped before it's built.**
+  `SettingsImportPreview::from_payload`'s `sanitize_for_preview` strips control characters and caps
+  at 100 characters (`MAX_PREVIEW_STRING_LEN`) for every base URL and the custom image name — a
+  review noted that, unlike the count- and boolean-derived fields the preview started with, these
+  are verbatim strings from a not-yet-trusted decrypted payload rendered directly into the
+  confirmation dialog. Unbounded, a single pathological value (very long, or holding embedded
+  newlines) could push the security warnings above the scroll fold in the dialog that exists
+  specifically to make them unmissable — the frontend's `<li>`/warning boxes also get `break-all`
+  as a second layer against the same failure mode.
+
 ## Testing
 
 Frontend tests use Vitest with jsdom environment and React Testing Library. Setup file at `src/test/setup.ts`. Run a single test file:
diff --git a/app/src-tauri/Cargo.lock b/app/src-tauri/Cargo.lock
index c75619d..d663f61 100644
--- a/app/src-tauri/Cargo.lock
+++ b/app/src-tauri/Cargo.lock
@@ -8,6 +8,41 @@ version = "2.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "320119579fcad9c21884f5c4861d16174d0e06250625266f50fe6898340abefa"
 
+[[package]]
+name = "aead"
+version = "0.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d122413f284cf2d62fb1b7db97e02edb8cda96d769b16e443a4f6195e35662b0"
+dependencies = [
+ "crypto-common",
+ "generic-array",
+]
+
+[[package]]
+name = "aes"
+version = "0.8.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b169f7a6d4742236a0a00c541b845991d0ac43e546831af1249753ab4c3aa3a0"
+dependencies = [
+ "cfg-if",
+ "cipher",
+ "cpufeatures",
+]
+
+[[package]]
+name = "aes-gcm"
+version = "0.10.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "831010a0f742e1209b3bcea8fab6a8e149051ba6099432c8cb2cc117dec3ead1"
+dependencies = [
+ "aead",
+ "aes",
+ "cipher",
+ "ctr",
+ "ghash",
+ "subtle",
+]
+
 [[package]]
 name = "aho-corasick"
 version = "1.1.4"
@@ -47,6 +82,18 @@ version = "1.0.102"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f202df86484c868dbad7eaa557ef785d5c66295e41b460ef922eca0723b842c"
 
+[[package]]
+name = "argon2"
+version = "0.5.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3c3610892ee6e0cbce8ae2700349fcf8f98adb0dbfbee85aec3c9179d29cc072"
+dependencies = [
+ "base64ct",
+ "blake2",
+ "cpufeatures",
+ "password-hash",
+]
+
 [[package]]
 name = "async-broadcast"
 version = "0.7.2"
@@ -280,6 +327,12 @@ version = "0.22.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
 
+[[package]]
+name = "base64ct"
+version = "1.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2af50177e190e07a26ab74f8b1efbfe2ef87da2116221318cb1c2e82baf7de06"
+
 [[package]]
 name = "bit-set"
 version = "0.8.0"
@@ -310,6 +363,15 @@ dependencies = [
  "serde_core",
 ]
 
+[[package]]
+name = "blake2"
+version = "0.10.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "46502ad458c9a52b69d4d4d32775c788b7a1b85e8bc9d482d92250fc0e3f8efe"
+dependencies = [
+ "digest",
+]
+
 [[package]]
 name = "block-buffer"
 version = "0.10.4"
@@ -569,6 +631,16 @@ dependencies = [
  "windows-link 0.2.1",
 ]
 
+[[package]]
+name = "cipher"
+version = "0.4.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "773f3b9af64447d2ce9850330c473515014aa235e6a783b02db81ff39e4a3dad"
+dependencies = [
+ "crypto-common",
+ "inout",
+]
+
 [[package]]
 name = "combine"
 version = "4.6.7"
@@ -694,6 +766,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "78c8292055d1c1df0cce5d180393dc8cce0abec0a7102adb6c7b1eef6016d60a"
 dependencies = [
  "generic-array",
+ "rand_core 0.6.4",
  "typenum",
 ]
 
@@ -753,6 +826,15 @@ version = "0.0.7"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "52560adf09603e58c9a7ee1fe1dcb95a16927b17c127f0ac02d6e768a0e25bc1"
 
+[[package]]
+name = "ctr"
+version = "0.9.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0369ee1ad671834580515889b80f2ea915f23b8be8d0daa4bbaf2ac5c7590835"
+dependencies = [
+ "cipher",
+]
+
 [[package]]
 name = "darling"
 version = "0.20.11"
@@ -923,6 +1005,7 @@ checksum = "9ed9a281f7bc9b7576e61468ba615a66a5c8cfdff42420a70aa82701a3b1e292"
 dependencies = [
  "block-buffer",
  "crypto-common",
+ "subtle",
 ]
 
 [[package]]
@@ -1550,6 +1633,16 @@ dependencies = [
  "syn 2.0.117",
 ]
 
+[[package]]
+name = "ghash"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f0d8a4362ccb29cb0b265253fb0a2728f592895ee6854fd9bc13f2ffda266ff1"
+dependencies = [
+ "opaque-debug",
+ "polyval",
+]
+
 [[package]]
 name = "gio"
 version = "0.18.4"
@@ -2114,6 +2207,15 @@ dependencies = [
  "cfb",
 ]
 
+[[package]]
+name = "inout"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "879f10e63c20629ecabbb64a8010319738c66a5cd0c29b02d63d272b03751d01"
+dependencies = [
+ "generic-array",
+]
+
 [[package]]
 name = "ipnet"
 version = "2.11.0"
@@ -2831,6 +2933,12 @@ version = "1.21.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "42f5e15c9953c5e4ccceeb2e7382a716482c34515315f7b03532b8b4e8393d2d"
 
+[[package]]
+name = "opaque-debug"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c08d65885ee38876c4f86fa503fb49d7b507c2b62552df7c70b2fce627e06381"
+
 [[package]]
 name = "open"
 version = "5.3.3"
@@ -2913,6 +3021,17 @@ dependencies = [
  "windows-link 0.2.1",
 ]
 
+[[package]]
+name = "password-hash"
+version = "0.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "346f04948ba92c43e8469c1ee6736c7563d71012b17d40745260fe106aac2166"
+dependencies = [
+ "base64ct",
+ "rand_core 0.6.4",
+ "subtle",
+]
+
 [[package]]
 name = "pathdiff"
 version = "0.2.3"
@@ -3194,6 +3313,18 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "polyval"
+version = "0.6.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9d1fe60d06143b2430aa532c94cfe9e29783047f06c0d7fd359a9a51b729fa25"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "opaque-debug",
+ "universal-hash",
+]
+
 [[package]]
 name = "potential_utf"
 version = "0.1.4"
@@ -5149,6 +5280,8 @@ dependencies = [
 name = "triple-c"
 version = "0.4.0"
 dependencies = [
+ "aes-gcm",
+ "argon2",
  "axum",
  "base64 0.22.1",
  "bollard",
@@ -5174,6 +5307,7 @@ dependencies = [
  "tokio",
  "tower-http",
  "uuid",
+ "zeroize",
 ]
 
 [[package]]
@@ -5287,6 +5421,16 @@ version = "0.2.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ebc1c04c71510c7f702b52b7c350734c9ff1295c464a03335b00bb84fc54f853"
 
+[[package]]
+name = "universal-hash"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fc1de2c688dc15305988b563c3854064043356019f97a4b46276fe734c4f07ea"
+dependencies = [
+ "crypto-common",
+ "subtle",
+]
+
 [[package]]
 name = "untrusted"
 version = "0.9.0"
diff --git a/app/src-tauri/Cargo.toml b/app/src-tauri/Cargo.toml
index b97b6cb..ebc9648 100644
--- a/app/src-tauri/Cargo.toml
+++ b/app/src-tauri/Cargo.toml
@@ -36,6 +36,9 @@ tower-http = { version = "0.6", features = ["cors"] }
 base64 = "0.22"
 rand = "0.9"
 local-ip-address = "0.6"
+argon2 = "0.5"
+aes-gcm = "0.10"
+zeroize = "1"
 
 [dev-dependencies]
 # `test-util` (not part of tokio's `full`) lets the auto-start retry tests run
diff --git a/app/src-tauri/src/commands/mod.rs b/app/src-tauri/src/commands/mod.rs
index bd2ecfc..cf2fb81 100644
--- a/app/src-tauri/src/commands/mod.rs
+++ b/app/src-tauri/src/commands/mod.rs
@@ -10,6 +10,7 @@ pub mod install_helper_commands;
 pub mod migration_commands;
 pub mod project_commands;
 pub mod settings_commands;
+pub mod settings_export_commands;
 pub mod stt_commands;
 pub mod terminal_commands;
 pub mod update_commands;
diff --git a/app/src-tauri/src/commands/settings_commands.rs b/app/src-tauri/src/commands/settings_commands.rs
index 5a8b0c6..13309bb 100644
--- a/app/src-tauri/src/commands/settings_commands.rs
+++ b/app/src-tauri/src/commands/settings_commands.rs
@@ -10,19 +10,24 @@ pub async fn get_settings(state: State<'_, AppState>) -> Result<AppSettings, Str
     Ok(state.settings_store.get())
 }
 
-#[tauri::command]
-pub async fn update_settings(
-    settings: AppSettings,
-    state: State<'_, AppState>,
-) -> Result<AppSettings, String> {
-    let before = state.settings_store.get();
-
+/// Everything `update_settings` refuses a save over, run against the store's
+/// *current* value and the incoming one.
+///
+/// Pulled out so a caller that does other, harder-to-undo work alongside a
+/// settings save — `settings_export_commands::apply_settings_import`
+/// restores three keychain secrets in the same command — can run this
+/// *first* and bail before touching anything, rather than discovering the
+/// rejection only when `update_settings` itself runs partway through.
+pub fn validate_settings_update(
+    before: &AppSettings,
+    incoming: &AppSettings,
+) -> Result<(), String> {
     // The global half of the same rule the project half gets in
     // `update_project`: a global custom env var is merged into every project's
     // container environment, so an unchecked name here reaches all of them.
     crate::models::validate_env_vars_update(
         &before.global_custom_env_vars,
-        &settings.global_custom_env_vars,
+        &incoming.global_custom_env_vars,
     )?;
 
     // The same for the two host paths this struct owns. `update_project`
@@ -40,14 +45,37 @@ pub async fn update_settings(
     crate::commands::project_commands::validate_mounted_host_path(
         "SSH key path",
         before.default_ssh_key_path.as_deref(),
-        settings.default_ssh_key_path.as_deref(),
+        incoming.default_ssh_key_path.as_deref(),
     )?;
     crate::commands::project_commands::validate_mounted_host_path(
         "CA certificate path",
         before.ca_cert_path.as_deref(),
-        settings.ca_cert_path.as_deref(),
+        incoming.ca_cert_path.as_deref(),
     )?;
 
+    // Third host path this struct owns, same reasoning: any project with
+    // `allow_docker_access` bind-mounts this path in as the Docker socket
+    // (`project_commands.rs`'s container creation), so an unchecked value
+    // here is a read-write bind mount of whatever it names into every such
+    // project's container.
+    crate::commands::project_commands::validate_mounted_host_path(
+        "Docker socket path",
+        before.docker_socket_path.as_deref(),
+        incoming.docker_socket_path.as_deref(),
+    )?;
+
+    Ok(())
+}
+
+#[tauri::command]
+pub async fn update_settings(
+    settings: AppSettings,
+    state: State<'_, AppState>,
+) -> Result<AppSettings, String> {
+    let before = state.settings_store.get();
+
+    validate_settings_update(&before, &settings)?;
+
     let saved = state.settings_store.update(settings)?;
 
     // Persisting a setting is not the same as applying it. The gateway is the
@@ -122,7 +150,10 @@ async fn reconcile_gateway(before: &GatewaySettings, after: &GatewaySettings) {
         GatewayAction::StopIfRunning => {
             log::info!("Model gateway disabled in settings — stopping the container");
             if let Err(e) = docker::gateway::stop_gateway_container().await {
-                log::error!("Failed to stop the model gateway after it was disabled: {}", e);
+                log::error!(
+                    "Failed to stop the model gateway after it was disabled: {}",
+                    e
+                );
             }
         }
         GatewayAction::RestartIfRunning => {
@@ -138,10 +169,7 @@ async fn reconcile_gateway(before: &GatewaySettings, after: &GatewaySettings) {
 }
 
 #[tauri::command]
-pub async fn pull_image(
-    image_name: String,
-    app_handle: tauri::AppHandle,
-) -> Result<(), String> {
+pub async fn pull_image(image_name: String, app_handle: tauri::AppHandle) -> Result<(), String> {
     use tauri::Emitter;
     docker::pull_image(&image_name, move |msg| {
         let _ = app_handle.emit("image-pull-progress", msg);
@@ -334,7 +362,10 @@ mod tests {
         let before = enabled_gateway();
         let mut after = before.clone();
         after.enabled = false;
-        assert_eq!(gateway_action(&before, &after), GatewayAction::StopIfRunning);
+        assert_eq!(
+            gateway_action(&before, &after),
+            GatewayAction::StopIfRunning
+        );
         // Still true when it was already off — a stray running container is
         // still a container that shouldn't be up.
         assert_eq!(gateway_action(&after, &after), GatewayAction::StopIfRunning);
diff --git a/app/src-tauri/src/commands/settings_export_commands.rs b/app/src-tauri/src/commands/settings_export_commands.rs
new file mode 100644
index 0000000..1bdd35b
--- /dev/null
+++ b/app/src-tauri/src/commands/settings_export_commands.rs
@@ -0,0 +1,654 @@
+//! Settings export/import — see triple-c#35.
+//!
+//! Exports the *host* environment (global `AppSettings` plus the global
+//! secrets kept in the OS keychain: the shared Claude Code OAuth login and
+//! the model gateway's two keys), encrypted with a user-chosen password —
+//! see `storage::settings_crypto` for the actual cryptography. Deliberately
+//! out of scope: per-project settings, per-project secrets, and anything
+//! living in a project's Docker volumes.
+//!
+//! **The save/open dialogs are opened from Rust**, the same pattern
+//! `file_commands.rs`'s `pick_save_path`/`pick_files_to_upload` already
+//! establish and document at length: a frontend-driven dialog handing Rust a
+//! host path string is the exact shape of bug that produced this app's past
+//! criticals, so the boundary here is drawn the same place. The frontend can
+//! ask for a picker; it cannot name a host path as an *input*. `preview_
+//! settings_import` resolves the chosen path itself and remembers it
+//! (`AppState::pending_settings_import`) so `apply_settings_import` re-reads
+//! the same file without the path ever crossing back over IPC.
+//!
+//! The *decrypted payload* is not cached between preview and apply — the
+//! password the frontend passes to each call is what it already held for
+//! the first, not a fresh secret extracted from the user, but nothing here
+//! keeps the plaintext itself — export/import secrets included — around for
+//! longer than one command's execution; `apply_settings_import` re-decrypts
+//! the file rather than reusing anything `preview_settings_import` computed.
+//!
+//! **This is new attack surface**: a settings export is a file one person
+//! can hand another and ask them to import, together with a password, and
+//! `apply_settings_import` applies whatever `AppSettings` it decrypts to
+//! wholesale — see the module doc on `models::settings_export` for the
+//! `web_terminal.access_token` carve-out a review of this feature found,
+//! and treat that as the standing example of the class of thing to keep
+//! checking for here, not a one-off fixed bug.
+
+#[cfg(test)]
+use std::path::Path;
+use std::path::PathBuf;
+
+use sha2::{Digest, Sha256};
+use tauri::State;
+use tauri_plugin_dialog::DialogExt;
+use zeroize::Zeroizing;
+
+use crate::models::{
+    AppSettings, ExportedSecrets, SettingsExportPayload, SettingsImportOutcome,
+    SettingsImportPreview, SETTINGS_EXPORT_FORMAT_VERSION,
+};
+use crate::storage::{secure, settings_crypto};
+use crate::AppState;
+
+/// What `preview_settings_import` pins so `apply_settings_import` can tell
+/// whether the file it's about to re-read is the same one the user actually
+/// saw a preview of. Confirming a preview is only meaningful if it's binding
+/// on what gets applied — without this, a file replaced on disk between the
+/// two calls (this app's own stated threat model is a file shared between
+/// people, which may sit in a synced or shared directory) would decrypt and
+/// apply silently different content than what the confirmation dialog showed.
+#[derive(Debug, Clone)]
+pub struct PendingSettingsImport {
+    path: PathBuf,
+    ciphertext_hash: [u8; 32],
+}
+
+fn hash_ciphertext(data: &[u8]) -> [u8; 32] {
+    Sha256::digest(data).into()
+}
+
+const FILE_EXTENSION: &str = "triplec";
+
+/// Enforced here, not only in the export modal: the frontend's minimum is a
+/// UX nudge, but `export_settings` is the actual boundary a weak password
+/// has to cross, and Argon2id's memory-hardness buys little against an
+/// attacker who can just try a three-character password directly.
+const MIN_PASSWORD_LEN: usize = 8;
+
+fn suggested_export_name() -> String {
+    // Timestamped so exporting more than once doesn't silently overwrite an
+    // earlier file just because the save dialog defaults to the same name.
+    format!(
+        "triple-c-settings-{}.{}",
+        chrono::Utc::now().format("%Y%m%d-%H%M%S"),
+        FILE_EXTENSION
+    )
+}
+
+async fn pick_export_save_path(window: &tauri::Window, suggested: &str) -> Option<PathBuf> {
+    let (tx, rx) = tokio::sync::oneshot::channel();
+    window
+        .dialog()
+        .file()
+        .set_parent(window)
+        .set_title("Export Triple-C settings")
+        .set_file_name(suggested)
+        .add_filter("Triple-C settings export", &[FILE_EXTENSION])
+        .save_file(move |picked| {
+            let _ = tx.send(picked);
+        });
+    rx.await.ok().flatten().and_then(|p| p.into_path().ok())
+}
+
+async fn pick_import_open_path(window: &tauri::Window) -> Option<PathBuf> {
+    let (tx, rx) = tokio::sync::oneshot::channel();
+    window
+        .dialog()
+        .file()
+        .set_parent(window)
+        .set_title("Import Triple-C settings")
+        .add_filter("Triple-C settings export", &[FILE_EXTENSION])
+        .pick_file(move |picked| {
+            let _ = tx.send(picked);
+        });
+    rx.await.ok().flatten().and_then(|p| p.into_path().ok())
+}
+
+/// Gather the current global secrets, and hand back the `AppSettings` to
+/// export with the web-terminal token blanked out of it — see the module
+/// doc comment on `models::settings_export` for why that field cannot
+/// travel through `settings` like the rest of this struct.
+///
+/// A missing keychain secret reads as `None` — a keychain read failure is
+/// treated as "nothing to export" for that one entry rather than aborting
+/// the whole export, matching how the rest of this app degrades a keychain
+/// error to "absent" (`has_claude_oauth_token`, `has_gateway_api_key`)
+/// rather than surfacing it as a hard failure.
+fn split_settings_and_secrets(current: AppSettings) -> (AppSettings, ExportedSecrets) {
+    let mut settings = current;
+    let web_terminal_access_token = settings.web_terminal.access_token.take();
+
+    let secrets = ExportedSecrets {
+        claude_oauth_token: secure::get_claude_oauth_token().unwrap_or_default(),
+        gateway_api_key: secure::get_gateway_api_key().unwrap_or_default(),
+        gateway_master_key: secure::get_gateway_master_key().unwrap_or_default(),
+        web_terminal_access_token,
+    };
+
+    (settings, secrets)
+}
+
+/// Export the current global settings and secrets to a password-encrypted
+/// file. `Ok(false)` means the save dialog was dismissed — not an error, and
+/// deliberately distinguishable from one so the frontend shows nothing
+/// rather than a "failed" toast for a plain cancel.
+#[tauri::command]
+pub async fn export_settings(
+    password: String,
+    window: tauri::Window,
+    state: State<'_, AppState>,
+) -> Result<bool, String> {
+    // `.chars().count()` — Unicode scalar values, not bytes — to stay as
+    // close as this pair of languages allows to the frontend's `.length`
+    // check (UTF-16 code units); the two only diverge on astral-plane
+    // characters, which no reasonable password touches.
+    if password.chars().count() < MIN_PASSWORD_LEN {
+        return Err(format!(
+            "Use a password of at least {} characters.",
+            MIN_PASSWORD_LEN
+        ));
+    }
+
+    let Some(dest) = pick_export_save_path(&window, &suggested_export_name()).await else {
+        return Ok(false);
+    };
+
+    let (settings, secrets) = split_settings_and_secrets(state.settings_store.get());
+    if secrets.is_empty() {
+        log::info!("Exporting settings with no global secrets configured on this machine");
+    }
+
+    let payload = SettingsExportPayload {
+        format_version: SETTINGS_EXPORT_FORMAT_VERSION,
+        exported_at: chrono::Utc::now().to_rfc3339(),
+        app_version: env!("CARGO_PKG_VERSION").to_string(),
+        settings,
+        secrets,
+    };
+
+    let plaintext = Zeroizing::new(
+        serde_json::to_vec(&payload)
+            .map_err(|e| format!("Failed to prepare settings for export: {}", e))?,
+    );
+    let encrypted = settings_crypto::encrypt(&plaintext, &password)?;
+
+    std::fs::write(&dest, &encrypted).map_err(|e| format!("Failed to write export file: {}", e))?;
+
+    Ok(true)
+}
+
+/// Open a file picker, decrypt the chosen file with `password`, and return a
+/// preview (counts and presence flags only — never a secret value) for a
+/// confirmation UI. `Ok(None)` means the picker was dismissed.
+///
+/// Remembers the resolved path *and a hash of the file's ciphertext* in
+/// `AppState::pending_settings_import` for `apply_settings_import` to check
+/// against — does **not** remember the decrypted payload itself, so the
+/// password must be supplied again to actually apply it — seeing the preview
+/// is not the same as committing to it. The hash exists so it also can't be
+/// swapped out from under that commitment: `apply_settings_import` refuses to
+/// proceed if the file on disk no longer matches what was just previewed.
+#[tauri::command]
+pub async fn preview_settings_import(
+    password: String,
+    window: tauri::Window,
+    state: State<'_, AppState>,
+) -> Result<Option<SettingsImportPreview>, String> {
+    if password.is_empty() {
+        return Err("A password is required to open a settings export.".to_string());
+    }
+
+    let Some(path) = pick_import_open_path(&window).await else {
+        return Ok(None);
+    };
+
+    let encrypted = std::fs::read(&path).map_err(|e| format!("Failed to read export file: {}", e))?;
+    let payload = read_and_decrypt_bytes(&encrypted, &password)?;
+    let preview = SettingsImportPreview::from_payload(&payload);
+
+    *state.pending_settings_import.lock().await = Some(PendingSettingsImport {
+        path,
+        ciphertext_hash: hash_ciphertext(&encrypted),
+    });
+
+    Ok(Some(preview))
+}
+
+/// Apply the import a prior `preview_settings_import` call resolved a path
+/// for. Fails if no preview is pending — this is not a general "decrypt and
+/// apply this file" entry point, deliberately: seeing the preview first is
+/// required, not just encouraged, since it is the only place a user is told
+/// what an import is about to touch before it touches it. That requirement
+/// is only real if the file can't change out from under it, so this also
+/// refuses to proceed if the file's ciphertext no longer matches the hash
+/// `preview_settings_import` pinned — a file replaced on disk between the
+/// two calls (this feature's own threat model is a file shared between
+/// people, which may sit in a synced or shared directory) must not be able
+/// to apply silently different content than what the confirmation dialog
+/// showed.
+///
+/// Global settings are replaced wholesale — an import is "restore this
+/// environment," not a field-by-field merge. Global secrets are handled
+/// differently and on purpose: **only secrets actually present in the
+/// import are written**; a secret the export doesn't have is left alone on
+/// this machine rather than cleared, because an absent secret in the export
+/// means "the source machine never had this configured," not "delete this
+/// on import." A user who wants to clear a secret already has dedicated UI
+/// for that (signing out of shared auth, clearing the gateway key).
+///
+/// Order matters here, twice over.
+///
+/// First: the imported settings are **validated before any secret is
+/// written**, using the same checks `update_settings` itself runs
+/// (`settings_commands::validate_settings_update`). Restoring a secret is
+/// hard to undo unnoticed — a stale env-var-name rejection or a disallowed
+/// host path used to be caught only when `update_settings` ran, by which
+/// point the three keychain secrets below were already overwritten with the
+/// file's, each with a fresh rotation id, silently flagging every project
+/// container for recreation — while the error the user saw talked only
+/// about the rejected setting and said nothing about the credentials that
+/// had already moved. Failing this check first makes a rejected import
+/// leave nothing touched, matching what "the import failed" is supposed to
+/// mean.
+///
+/// Second, among the things that *do* get written: secrets are restored
+/// **before** the settings replace runs (which is what triggers
+/// `reconcile_gateway`), so a gateway recreation that replace provokes sees
+/// the final key material rather than racing it — restoring the other way
+/// round left a real window where the running gateway and the keychain
+/// briefly disagreed. A gateway *secret* alone (same shape, new key) is
+/// invisible to `reconcile_gateway`'s shape comparison, so this additionally
+/// nudges a running gateway container to recreate itself whenever a secret
+/// this import carried was actually written — otherwise the running
+/// container keeps serving the old key material indefinitely while every
+/// project container is handed the new one.
+///
+/// A keychain write failing is reported back rather than only logged: an
+/// import that silently restores two of three secrets but not the third
+/// must not read as unqualified success.
+///
+/// The pending import is only cleared on success. A failure here (rejected
+/// by the validation above, a stale-file mismatch, or some other error)
+/// leaves it pending so the frontend can let the user retry `apply` without
+/// making them pick the file and re-enter the password again — the
+/// preview's job was confirming *what* to import, not spending the one
+/// attempt at applying it.
+#[tauri::command]
+pub async fn apply_settings_import(
+    password: String,
+    state: State<'_, AppState>,
+) -> Result<SettingsImportOutcome, String> {
+    if password.is_empty() {
+        return Err("A password is required to import settings.".to_string());
+    }
+
+    let pending = state
+        .pending_settings_import
+        .lock()
+        .await
+        .clone()
+        .ok_or_else(|| "No import is pending — choose a file first.".to_string())?;
+
+    let encrypted = std::fs::read(&pending.path)
+        .map_err(|e| format!("Failed to read export file: {}", e))?;
+    if hash_ciphertext(&encrypted) != pending.ciphertext_hash {
+        return Err(
+            "This file changed since you reviewed it — choose it again to see an up-to-date preview."
+                .to_string(),
+        );
+    }
+    let payload = read_and_decrypt_bytes(&encrypted, &password)?;
+
+    let current = state.settings_store.get();
+
+    // The web-terminal token lives inside `AppSettings` itself rather than
+    // the keychain, so "leave an absent secret alone" has to be done by
+    // hand here: carry the destination's current token forward when the
+    // import doesn't have one, instead of letting the wholesale replace
+    // below blank it (every export writes `None` there — see
+    // `split_settings_and_secrets`).
+    let mut settings = payload.settings;
+    settings.web_terminal.access_token = non_blank(payload.secrets.web_terminal_access_token)
+        .or_else(|| current.web_terminal.access_token.clone());
+
+    crate::commands::settings_commands::validate_settings_update(&current, &settings)?;
+
+    let mut secret_restore_warnings = Vec::new();
+    let mut gateway_secret_changed = false;
+
+    if let Some(token) = non_blank(payload.secrets.claude_oauth_token) {
+        if let Err(e) = secure::store_claude_oauth_token(&token) {
+            log::warn!(
+                "Settings import: could not restore the shared Claude login: {}",
+                e
+            );
+            secret_restore_warnings
+                .push(format!("Could not restore your shared Claude login: {}", e));
+        }
+    }
+    if let Some(key) = non_blank(payload.secrets.gateway_api_key) {
+        match secure::store_gateway_api_key(&key) {
+            Ok(()) => gateway_secret_changed = true,
+            Err(e) => {
+                log::warn!(
+                    "Settings import: could not restore the gateway provider API key: {}",
+                    e
+                );
+                secret_restore_warnings.push(format!(
+                    "Could not restore the gateway provider API key: {}",
+                    e
+                ));
+            }
+        }
+    }
+    if let Some(key) = non_blank(payload.secrets.gateway_master_key) {
+        match secure::store_gateway_master_key(&key) {
+            Ok(()) => gateway_secret_changed = true,
+            Err(e) => {
+                log::warn!(
+                    "Settings import: could not restore the gateway master key: {}",
+                    e
+                );
+                secret_restore_warnings
+                    .push(format!("Could not restore the gateway master key: {}", e));
+            }
+        }
+    }
+
+    let saved =
+        crate::commands::settings_commands::update_settings(settings, state.clone()).await?;
+
+    // `reconcile_gateway` (inside `update_settings`) only reacts to a changed
+    // *shape* — port, provider, base URL, models — because that's what's
+    // rendered into the container's config. A secret changing with the shape
+    // held constant is invisible to it, so a running gateway container would
+    // otherwise keep serving the old key material forever after an import
+    // that restored a new one, while `docker::gateway`'s own fingerprint
+    // (which does include the secret rotation id) means the *next* unrelated
+    // settings save would suddenly and confusingly recreate it instead.
+    if gateway_secret_changed && saved.gateway.enabled {
+        match crate::docker::gateway::gateway_container_presence().await {
+            Ok((true, true)) => {
+                if let Err(e) = crate::docker::gateway::ensure_gateway_running(&saved.gateway).await
+                {
+                    log::error!(
+                        "Settings import: could not apply the restored gateway credentials to the running gateway container: {}",
+                        e
+                    );
+                }
+            }
+            Ok(_) => {}
+            Err(e) => log::debug!("Settings import: gateway reconcile skipped ({})", e),
+        }
+    }
+
+    state.pending_settings_import.lock().await.take();
+
+    Ok(SettingsImportOutcome {
+        settings: saved,
+        secret_restore_warnings,
+    })
+}
+
+fn non_blank(value: Option<String>) -> Option<String> {
+    value.filter(|v| !v.trim().is_empty())
+}
+
+/// Only the field `read_and_decrypt` needs before deciding whether the rest
+/// of the payload is even worth attempting to parse.
+#[derive(serde::Deserialize)]
+struct FormatVersionProbe {
+    format_version: u32,
+}
+
+/// Read and decrypt an export file at `path`, then parse it — see
+/// `read_and_decrypt_bytes` for why the format-version check runs before the
+/// full parse. Every real caller already has the file's bytes in hand by the
+/// time it needs this (`preview_settings_import`/`apply_settings_import`
+/// both hash the ciphertext first) and calls `read_and_decrypt_bytes`
+/// directly to avoid reading the file twice; this path-based wrapper only
+/// exists now for tests that don't need that.
+#[cfg(test)]
+fn read_and_decrypt(path: &Path, password: &str) -> Result<SettingsExportPayload, String> {
+    let encrypted =
+        std::fs::read(path).map_err(|e| format!("Failed to read export file: {}", e))?;
+    read_and_decrypt_bytes(&encrypted, password)
+}
+
+/// Decrypt and parse an already-read export file's bytes, checking the
+/// format version **before** attempting to deserialize the full payload.
+///
+/// That ordering is not just tidiness: a version bump that isn't
+/// deserialize-compatible (a field's type changes, not just a new
+/// `#[serde(default)]`-covered one) is exactly the case this check exists
+/// for, and parsing the full struct first would fail on the shape mismatch
+/// before the version check ever ran, surfacing a raw parse error instead
+/// of "update Triple-C" — and, more seriously, `serde_json`'s type-mismatch
+/// errors quote the offending value inline. This file is not attacker
+/// content in the usual sense (it must still decrypt under the right
+/// password), but the plaintext it decrypts to can hold a live credential,
+/// so neither error path below ever interpolates what `serde_json`
+/// actually says — only a fixed, generic message.
+fn read_and_decrypt_bytes(encrypted: &[u8], password: &str) -> Result<SettingsExportPayload, String> {
+    let plaintext = settings_crypto::decrypt(encrypted, password)?;
+
+    let probe: FormatVersionProbe = serde_json::from_slice(&plaintext)
+        .map_err(|_| "This file doesn't look like a valid settings export.".to_string())?;
+    if probe.format_version > SETTINGS_EXPORT_FORMAT_VERSION {
+        return Err(format!(
+            "This export was made by a newer version of Triple-C (format {}, this app supports up to {}). \
+             Update Triple-C before importing it.",
+            probe.format_version, SETTINGS_EXPORT_FORMAT_VERSION
+        ));
+    }
+
+    serde_json::from_slice(&plaintext).map_err(|_| {
+        "This file doesn't look like a valid settings export (unexpected shape).".to_string()
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn non_blank_treats_whitespace_only_as_absent() {
+        assert_eq!(non_blank(Some("   ".to_string())), None);
+        assert_eq!(non_blank(Some("".to_string())), None);
+        assert_eq!(non_blank(None), None);
+        assert_eq!(non_blank(Some(" a ".to_string())), Some(" a ".to_string()));
+    }
+
+    #[test]
+    fn ciphertext_hashing_is_deterministic_and_tamper_sensitive() {
+        // What `apply_settings_import` compares against the pinned hash from
+        // `preview_settings_import` to detect a file swapped out from under a
+        // pending import — this only defends anything if identical bytes
+        // always hash identically and any change to those bytes changes the
+        // hash.
+        let bytes = b"pretend this is an encrypted export file";
+        assert_eq!(hash_ciphertext(bytes), hash_ciphertext(bytes));
+
+        let mut tampered = bytes.to_vec();
+        tampered[0] ^= 0xFF;
+        assert_ne!(hash_ciphertext(bytes), hash_ciphertext(&tampered));
+    }
+
+    fn write_export(
+        dir: &std::path::Path,
+        name: &str,
+        payload: &SettingsExportPayload,
+        password: &str,
+    ) -> PathBuf {
+        write_raw_export(dir, name, &serde_json::to_value(payload).unwrap(), password)
+    }
+
+    /// Like `write_export`, but takes an arbitrary `serde_json::Value` rather
+    /// than a real `SettingsExportPayload` — for fixtures that are
+    /// deliberately not shape-compatible, which the typed helper above can't
+    /// produce at all.
+    fn write_raw_export(
+        dir: &std::path::Path,
+        name: &str,
+        value: &serde_json::Value,
+        password: &str,
+    ) -> PathBuf {
+        let plaintext = serde_json::to_vec(value).unwrap();
+        let encrypted = settings_crypto::encrypt(&plaintext, password).unwrap();
+        let path = dir.join(name);
+        std::fs::write(&path, &encrypted).unwrap();
+        path
+    }
+
+    #[test]
+    fn splitting_settings_moves_the_web_terminal_token_out_rather_than_copying_it() {
+        let mut settings = AppSettings::default();
+        settings.web_terminal.access_token = Some("super-secret-token".to_string());
+
+        let (settings, secrets) = split_settings_and_secrets(settings);
+
+        assert_eq!(settings.web_terminal.access_token, None);
+        assert_eq!(
+            secrets.web_terminal_access_token,
+            Some("super-secret-token".to_string())
+        );
+    }
+
+    #[test]
+    fn splitting_settings_with_no_token_leaves_it_absent_on_both_sides() {
+        let (settings, secrets) = split_settings_and_secrets(AppSettings::default());
+
+        assert_eq!(settings.web_terminal.access_token, None);
+        assert_eq!(secrets.web_terminal_access_token, None);
+    }
+
+    fn sample_payload(format_version: u32) -> SettingsExportPayload {
+        SettingsExportPayload {
+            format_version,
+            exported_at: "2026-08-27T00:00:00Z".to_string(),
+            app_version: "0.4.14".to_string(),
+            settings: AppSettings::default(),
+            secrets: ExportedSecrets::default(),
+        }
+    }
+
+    fn temp_dir(name: &str) -> PathBuf {
+        let dir = std::env::temp_dir().join(format!(
+            "triple-c-settings-export-test-{}-{}",
+            name,
+            uuid::Uuid::new_v4().simple()
+        ));
+        std::fs::create_dir_all(&dir).unwrap();
+        dir
+    }
+
+    #[test]
+    fn a_file_from_a_newer_format_is_refused_before_the_full_shape_is_parsed() {
+        // Shape-incompatible with the *current* `SettingsExportPayload` (a
+        // future version could easily have changed `settings` from an object
+        // to something else) as well as newer — so this only passes under
+        // the probe-first ordering. Parsing the full struct first (the old
+        // behavior) would fail on the shape mismatch and never reach the
+        // version check, producing the "unexpected shape" message instead of
+        // "newer version" / "Update Triple-C".
+        let dir = temp_dir("newer-format");
+        let path = write_raw_export(
+            &dir,
+            "export.triplec",
+            &serde_json::json!({
+                "format_version": SETTINGS_EXPORT_FORMAT_VERSION + 1,
+                "exported_at": "2026-08-27T00:00:00Z",
+                "app_version": "9.9.9",
+                "settings": "this-app-version-stores-settings-differently",
+                "secrets": {},
+            }),
+            "correct password",
+        );
+
+        let err = read_and_decrypt(&path, "correct password").unwrap_err();
+        assert!(err.contains("newer version"), "unexpected message: {}", err);
+        assert!(err.contains("Update Triple-C"));
+
+        std::fs::remove_dir_all(&dir).ok();
+    }
+
+    #[test]
+    fn a_file_at_the_current_format_is_accepted() {
+        let dir = temp_dir("current-format");
+        let path = write_export(
+            &dir,
+            "export.triplec",
+            &sample_payload(SETTINGS_EXPORT_FORMAT_VERSION),
+            "correct password",
+        );
+
+        let payload = read_and_decrypt(&path, "correct password").unwrap();
+        assert_eq!(payload.format_version, SETTINGS_EXPORT_FORMAT_VERSION);
+
+        std::fs::remove_dir_all(&dir).ok();
+    }
+
+    #[test]
+    fn a_malformed_payload_produces_a_generic_error_not_a_raw_serde_message() {
+        // A `format_version` the probe accepts, but a `settings` field of
+        // the wrong *type* rather than just a missing field — this is what
+        // makes `serde_json` produce an "invalid type: string `...`, expected
+        // struct AppSettings" error that quotes the offending value
+        // verbatim. That value here stands in for plaintext that, in a real
+        // export, could be a live credential — the assertion below is only
+        // meaningful against a fixture that actually exercises serde's
+        // value-quoting behavior, which a merely-missing-field fixture does
+        // not.
+        let dir = temp_dir("malformed");
+        let path = write_raw_export(
+            &dir,
+            "export.triplec",
+            &serde_json::json!({
+                "format_version": SETTINGS_EXPORT_FORMAT_VERSION,
+                "exported_at": "2026-08-27T00:00:00Z",
+                "app_version": "0.4.14",
+                "settings": "NOT-A-REAL-CREDENTIAL-abc123",
+                "secrets": {},
+            }),
+            "correct password",
+        );
+
+        let err = read_and_decrypt(&path, "correct password").unwrap_err();
+        assert!(
+            !err.contains("NOT-A-REAL-CREDENTIAL-abc123"),
+            "leaked plaintext into the error: {}",
+            err
+        );
+        assert!(err.contains("doesn't look like a valid settings export"));
+
+        std::fs::remove_dir_all(&dir).ok();
+    }
+
+    #[test]
+    fn the_wrong_password_is_reported_without_a_version_check_ever_running() {
+        let dir = temp_dir("wrong-password");
+        let path = write_export(
+            &dir,
+            "export.triplec",
+            &sample_payload(SETTINGS_EXPORT_FORMAT_VERSION),
+            "correct password",
+        );
+
+        let err = read_and_decrypt(&path, "wrong password").unwrap_err();
+        assert!(
+            err.contains("Wrong password"),
+            "unexpected message: {}",
+            err
+        );
+
+        std::fs::remove_dir_all(&dir).ok();
+    }
+}
diff --git a/app/src-tauri/src/lib.rs b/app/src-tauri/src/lib.rs
index 2bbe8f1..b789ad8 100644
--- a/app/src-tauri/src/lib.rs
+++ b/app/src-tauri/src/lib.rs
@@ -29,6 +29,21 @@ pub struct AppState {
     pub auth_bridge: Arc<AuthBridgeManager>,
     pub web_terminal_server: Arc<tokio::sync::Mutex<Option<WebTerminalServer>>>,
     pub lifecycle: Arc<Lifecycle>,
+    /// The file `preview_settings_import` last decrypted successfully, held
+    /// so `apply_settings_import` can re-read and re-decrypt the same file
+    /// without the frontend ever passing a host path back to Rust as an
+    /// argument — see the doc comment on `commands::settings_export_commands`
+    /// for why that direction specifically is the one this app treats as
+    /// dangerous. Deliberately re-decrypted rather than cached in plaintext:
+    /// nothing here holds a decrypted secret in memory for longer than one
+    /// command's execution.
+    ///
+    /// Also pins a hash of the file's ciphertext at preview time, so
+    /// `apply_settings_import` can refuse to proceed if the file on disk
+    /// changed underneath the pending import — otherwise confirming a
+    /// preview is not actually binding on what gets applied.
+    pub pending_settings_import:
+        Arc<tokio::sync::Mutex<Option<commands::settings_export_commands::PendingSettingsImport>>>,
 }
 
 // ─────────────────────────────────────────────────────────────────────────────
@@ -222,6 +237,7 @@ pub fn run() {
             auth_bridge,
             web_terminal_server: Arc::new(tokio::sync::Mutex::new(None)),
             lifecycle,
+            pending_settings_import: Arc::new(tokio::sync::Mutex::new(None)),
         })
         .setup(move |app| {
             match tauri::image::Image::from_bytes(include_bytes!("../icons/icon.png")) {
@@ -494,6 +510,10 @@ pub fn run() {
             commands::settings_commands::inspect_ca_cert_path,
             commands::settings_commands::list_aws_profiles,
             commands::settings_commands::detect_host_timezone,
+            // Settings export/import
+            commands::settings_export_commands::export_settings,
+            commands::settings_export_commands::preview_settings_import,
+            commands::settings_export_commands::apply_settings_import,
             // Terminal
             commands::terminal_commands::open_terminal_session,
             commands::terminal_commands::terminal_input,
diff --git a/app/src-tauri/src/models/mod.rs b/app/src-tauri/src/models/mod.rs
index e442ae7..a868bff 100644
--- a/app/src-tauri/src/models/mod.rs
+++ b/app/src-tauri/src/models/mod.rs
@@ -3,6 +3,7 @@ pub mod container_config;
 pub mod app_settings;
 pub mod gateway_settings;
 pub mod migration;
+pub mod settings_export;
 pub mod update_info;
 
 pub use project::*;
@@ -10,4 +11,5 @@ pub use container_config::*;
 pub use app_settings::*;
 pub use gateway_settings::*;
 pub use migration::*;
+pub use settings_export::*;
 pub use update_info::*;
diff --git a/app/src-tauri/src/models/settings_export.rs b/app/src-tauri/src/models/settings_export.rs
new file mode 100644
index 0000000..cf6c5d4
--- /dev/null
+++ b/app/src-tauri/src/models/settings_export.rs
@@ -0,0 +1,366 @@
+//! Settings export/import — see triple-c#35.
+//!
+//! `SettingsExportPayload` is the whole plaintext export before encryption
+//! and after decryption (see `storage::settings_crypto`). It bundles
+//! `AppSettings` — with one field carved out, see below — with the global
+//! secrets that live in the OS keychain instead: the shared Claude Code
+//! OAuth login and the model gateway's two keys. Per-project settings,
+//! per-project secrets, and anything living in a project's Docker volumes
+//! are deliberately out of scope: this exports the *host* environment, not
+//! any one project's.
+//!
+//! **`AppSettings` is not entirely the non-secret shape it looks like.**
+//! `WebTerminalSettings::access_token` is a live bearer credential for a
+//! server that binds every interface, stored as a plain field on the
+//! struct that is otherwise safe to treat as config. A review of this
+//! feature caught it: exporting `AppSettings` wholesale would have carried
+//! that token along as if it were as inert as a port number, and — worse —
+//! importing it would apply `web_terminal.enabled` and the token together
+//! with no more warning than any other setting, letting a crafted export
+//! silently stand up a LAN-listening terminal server with an
+//! attacker-known token on the next launch. `export_settings` /
+//! `apply_settings_import` blank this field out of the `settings` they
+//! read from and write to, and it travels only through
+//! [`ExportedSecrets::web_terminal_access_token`] instead, with the same
+//! "only overwrite what the import actually has" treatment as the other
+//! three secrets.
+
+use serde::{Deserialize, Serialize};
+
+use super::{AppSettings, ImageSource};
+
+/// Bumped when the shape of [`SettingsExportPayload`] changes in a way that
+/// isn't just an additive, `#[serde(default)]`-covered field — e.g. if a
+/// field is ever removed or its meaning changes. `apply_settings_import`
+/// checks this before touching anything.
+pub const SETTINGS_EXPORT_FORMAT_VERSION: u32 = 1;
+
+/// The global secrets bundled into an export. Deliberately a separate struct
+/// from `AppSettings`: these live in the OS keychain, never in
+/// `settings.json`, and — outside of this export/import flow — the values
+/// themselves never cross into the frontend; see the doc comments on
+/// `storage::secure::get_gateway_api_key` and
+/// `commands::settings_export_commands` for why that boundary matters here
+/// too.
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct ExportedSecrets {
+    #[serde(default)]
+    pub claude_oauth_token: Option<String>,
+    #[serde(default)]
+    pub gateway_api_key: Option<String>,
+    #[serde(default)]
+    pub gateway_master_key: Option<String>,
+    /// See the module doc comment — this is `AppSettings::web_terminal
+    /// .access_token`, carved out because it is a live bearer credential,
+    /// not config, despite living on a struct that is otherwise safe to
+    /// export wholesale.
+    #[serde(default)]
+    pub web_terminal_access_token: Option<String>,
+}
+
+impl ExportedSecrets {
+    pub fn is_empty(&self) -> bool {
+        let blank = |s: &Option<String>| s.as_deref().is_none_or(|v| v.trim().is_empty());
+        blank(&self.claude_oauth_token)
+            && blank(&self.gateway_api_key)
+            && blank(&self.gateway_master_key)
+            && blank(&self.web_terminal_access_token)
+    }
+}
+
+/// What `apply_settings_import` hands back: the settings that were actually
+/// saved, plus a human-readable note for each keychain secret this import
+/// carried but could not be restored. A keychain write failing partway
+/// through must not read as unqualified success just because the settings
+/// half of the import went through.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct SettingsImportOutcome {
+    pub settings: AppSettings,
+    #[serde(default)]
+    pub secret_restore_warnings: Vec<String>,
+}
+
+/// The full plaintext payload — this is what gets encrypted on export and
+/// what decryption recovers on import. Never written to disk unencrypted;
+/// see `storage::settings_crypto`.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct SettingsExportPayload {
+    pub format_version: u32,
+    /// RFC3339. Purely informational — shown in the import preview so a user
+    /// picking between a few old export files has something to go on.
+    pub exported_at: String,
+    /// The exporting app's `CARGO_PKG_VERSION`. Also informational: every
+    /// field below already round-trips through `#[serde(default)]`-covered
+    /// `AppSettings`, so an older or newer export still deserializes; this is
+    /// for a human to notice "this is from a much older version" if an import
+    /// ever looks wrong, not something the code branches on.
+    pub app_version: String,
+    pub settings: AppSettings,
+    #[serde(default)]
+    pub secrets: ExportedSecrets,
+}
+
+/// What `preview_settings_import` hands the frontend before anything is
+/// applied — counts and presence flags only, **never** a secret value itself,
+/// so this type is safe to return across the IPC boundary and render
+/// directly. The confirmation UI is built from this.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct SettingsImportPreview {
+    pub exported_at: String,
+    pub app_version: String,
+    pub custom_env_var_count: usize,
+    pub gateway_model_count: usize,
+    pub has_claude_code_settings: bool,
+    pub has_claude_oauth_token: bool,
+    pub has_gateway_api_key: bool,
+    pub has_gateway_master_key: bool,
+    pub has_web_terminal_access_token: bool,
+    /// Whether the imported settings turn the web terminal on. Named
+    /// separately from the token above: `enabled` and the token are two
+    /// different fields, either can be true without the other, and
+    /// "this import turns on a service that listens on your network" is
+    /// exactly the kind of change a wholesale settings replace must not
+    /// bury in a generic "settings replaced" line — see the module doc
+    /// comment on why this field exists at all.
+    pub enables_web_terminal: bool,
+    /// Non-blank custom base URLs the import would set, so a redirect of
+    /// model traffic to somewhere other than the usual provider is visible
+    /// at import time rather than discovered later. These are endpoints, not
+    /// secrets — safe to show verbatim, unlike everything above.
+    #[serde(default)]
+    pub ollama_base_url: Option<String>,
+    #[serde(default)]
+    pub llamacpp_base_url: Option<String>,
+    #[serde(default)]
+    pub openai_compatible_base_url: Option<String>,
+    #[serde(default)]
+    pub gateway_api_base: Option<String>,
+    /// Whether the import sets a custom Docker image, and its name if so —
+    /// disclosed for the same reason as the base URLs above, and arguably
+    /// more sharply: this is the image *every* project container is created
+    /// from (`models::container_config::resolve_image_name`), so a crafted
+    /// export pointing it at an attacker-controlled image is a path to
+    /// running arbitrary code with whatever a project's containers are
+    /// allowed to reach (the Docker socket, an SSH key, project files) —
+    /// not merely a redirected API endpoint.
+    #[serde(default)]
+    pub image_source: ImageSource,
+    #[serde(default)]
+    pub custom_image_name: Option<String>,
+}
+
+/// A cap on how much of a decrypted, not-yet-trusted string gets echoed back
+/// into a preview a user reads and a UI renders without truncation of its
+/// own. Applied to every field above that carries free-form text straight
+/// from the import file rather than a count or a boolean — a base URL or an
+/// image name a hostile export author controls has had no validation done
+/// on it yet at preview time, and nothing stops it from being pathological
+/// (embedded control characters, or long enough to blow out the confirmation
+/// dialog and push the security warnings below it off screen).
+const MAX_PREVIEW_STRING_LEN: usize = 100;
+
+fn sanitize_for_preview(value: &str) -> String {
+    let cleaned: String = value.chars().filter(|c| !c.is_control()).collect();
+    let trimmed = cleaned.trim();
+    if trimmed.chars().count() > MAX_PREVIEW_STRING_LEN {
+        let truncated: String = trimmed.chars().take(MAX_PREVIEW_STRING_LEN).collect();
+        format!("{}…", truncated)
+    } else {
+        trimmed.to_string()
+    }
+}
+
+impl SettingsImportPreview {
+    pub fn from_payload(payload: &SettingsExportPayload) -> Self {
+        let non_blank = |s: &Option<String>| s.as_deref().is_some_and(|v| !v.trim().is_empty());
+        let sanitized_non_blank = |s: &Option<String>| {
+            s.as_deref()
+                .map(sanitize_for_preview)
+                .filter(|v| !v.is_empty())
+        };
+        Self {
+            exported_at: payload.exported_at.clone(),
+            app_version: payload.app_version.clone(),
+            custom_env_var_count: payload.settings.global_custom_env_vars.len(),
+            gateway_model_count: payload.settings.gateway.models.len(),
+            has_claude_code_settings: payload.settings.global_claude_code_settings.is_some(),
+            has_claude_oauth_token: non_blank(&payload.secrets.claude_oauth_token),
+            has_gateway_api_key: non_blank(&payload.secrets.gateway_api_key),
+            has_gateway_master_key: non_blank(&payload.secrets.gateway_master_key),
+            has_web_terminal_access_token: non_blank(&payload.secrets.web_terminal_access_token),
+            enables_web_terminal: payload.settings.web_terminal.enabled,
+            ollama_base_url: sanitized_non_blank(&payload.settings.global_ollama.base_url),
+            llamacpp_base_url: sanitized_non_blank(&payload.settings.global_llamacpp.base_url),
+            openai_compatible_base_url: sanitized_non_blank(
+                &payload.settings.global_openai_compatible.base_url,
+            ),
+            gateway_api_base: sanitized_non_blank(&payload.settings.gateway.api_base),
+            image_source: payload.settings.image_source.clone(),
+            custom_image_name: sanitized_non_blank(&payload.settings.custom_image_name),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::models::AppSettings;
+
+    fn payload_with(secrets: ExportedSecrets) -> SettingsExportPayload {
+        let settings = AppSettings {
+            global_custom_env_vars: vec![
+                crate::models::EnvVar {
+                    key: "A".to_string(),
+                    value: "1".to_string(),
+                },
+                crate::models::EnvVar {
+                    key: "B".to_string(),
+                    value: "2".to_string(),
+                },
+            ],
+            ..AppSettings::default()
+        };
+        SettingsExportPayload {
+            format_version: SETTINGS_EXPORT_FORMAT_VERSION,
+            exported_at: "2026-08-27T00:00:00Z".to_string(),
+            app_version: "0.4.14".to_string(),
+            settings,
+            secrets,
+        }
+    }
+
+    #[test]
+    fn the_preview_never_carries_a_secret_value() {
+        let payload = payload_with(ExportedSecrets {
+            claude_oauth_token: Some("sk-super-secret-token".to_string()),
+            gateway_api_key: Some("sk-another-secret".to_string()),
+            gateway_master_key: Some("sk-triple-c-yet-another".to_string()),
+            web_terminal_access_token: Some("wt-super-secret-token".to_string()),
+        });
+        let preview = SettingsImportPreview::from_payload(&payload);
+        let serialized = serde_json::to_string(&preview).unwrap();
+
+        assert!(!serialized.contains("sk-super-secret-token"));
+        assert!(!serialized.contains("sk-another-secret"));
+        assert!(!serialized.contains("sk-triple-c-yet-another"));
+        assert!(!serialized.contains("wt-super-secret-token"));
+        assert!(preview.has_claude_oauth_token);
+        assert!(preview.has_gateway_api_key);
+        assert!(preview.has_gateway_master_key);
+        assert!(preview.has_web_terminal_access_token);
+    }
+
+    #[test]
+    fn a_blank_secret_reads_as_absent_in_the_preview() {
+        // A keychain entry that exists but holds only whitespace must not
+        // read as "present" — same "blank counts as absent" rule the
+        // keychain layer itself applies when storing these.
+        let payload = payload_with(ExportedSecrets {
+            claude_oauth_token: Some("   ".to_string()),
+            gateway_api_key: None,
+            gateway_master_key: None,
+            web_terminal_access_token: Some("   ".to_string()),
+        });
+        let preview = SettingsImportPreview::from_payload(&payload);
+        assert!(!preview.has_claude_oauth_token);
+        assert!(!preview.has_gateway_api_key);
+        assert!(!preview.has_gateway_master_key);
+        assert!(!preview.has_web_terminal_access_token);
+    }
+
+    #[test]
+    fn enabling_the_web_terminal_is_surfaced_regardless_of_whether_a_token_came_with_it() {
+        // `enabled` and the token are independent fields — a crafted export
+        // could set one without the other, and both are worth a user's
+        // attention: this is the field that exists specifically so "this
+        // import turns on a service that listens on your network" cannot
+        // hide inside a generic "settings replaced" summary.
+        let mut payload = payload_with(ExportedSecrets::default());
+        payload.settings.web_terminal.enabled = true;
+        let preview = SettingsImportPreview::from_payload(&payload);
+        assert!(preview.enables_web_terminal);
+        assert!(!preview.has_web_terminal_access_token);
+    }
+
+    #[test]
+    fn custom_base_urls_are_surfaced_but_blank_ones_read_as_absent() {
+        let mut payload = payload_with(ExportedSecrets::default());
+        payload.settings.global_ollama.base_url = Some("http://attacker.example:11434".to_string());
+        payload.settings.global_llamacpp.base_url = Some("   ".to_string());
+        payload.settings.gateway.api_base = Some("https://gateway.example/v1".to_string());
+
+        let preview = SettingsImportPreview::from_payload(&payload);
+        assert_eq!(
+            preview.ollama_base_url.as_deref(),
+            Some("http://attacker.example:11434")
+        );
+        assert_eq!(preview.llamacpp_base_url, None);
+        assert_eq!(preview.openai_compatible_base_url, None);
+        assert_eq!(
+            preview.gateway_api_base.as_deref(),
+            Some("https://gateway.example/v1")
+        );
+    }
+
+    #[test]
+    fn counts_reflect_the_real_settings() {
+        let payload = payload_with(ExportedSecrets::default());
+        let preview = SettingsImportPreview::from_payload(&payload);
+        assert_eq!(preview.custom_env_var_count, 2);
+    }
+
+    #[test]
+    fn an_empty_secrets_bundle_reports_itself_as_empty() {
+        assert!(ExportedSecrets::default().is_empty());
+        assert!(!ExportedSecrets {
+            claude_oauth_token: Some("x".to_string()),
+            ..Default::default()
+        }
+        .is_empty());
+    }
+
+    #[test]
+    fn a_secrets_bundle_holding_only_whitespace_still_reports_itself_as_empty() {
+        // Matches the "blank counts as absent" rule every other consumer of
+        // these fields applies (`has_claude_oauth_token` and friends above) —
+        // a keychain entry that exists but holds only whitespace carries
+        // nothing usable, so the export-time "nothing to export" log line
+        // must still fire for it.
+        assert!(ExportedSecrets {
+            claude_oauth_token: Some("   ".to_string()),
+            ..Default::default()
+        }
+        .is_empty());
+    }
+
+    #[test]
+    fn a_custom_docker_image_is_surfaced() {
+        let mut payload = payload_with(ExportedSecrets::default());
+        payload.settings.image_source = crate::models::ImageSource::Custom;
+        payload.settings.custom_image_name = Some("ghcr.io/attacker/triple-c:latest".to_string());
+
+        let preview = SettingsImportPreview::from_payload(&payload);
+        assert_eq!(preview.image_source, crate::models::ImageSource::Custom);
+        assert_eq!(
+            preview.custom_image_name.as_deref(),
+            Some("ghcr.io/attacker/triple-c:latest")
+        );
+    }
+
+    #[test]
+    fn preview_strings_are_stripped_of_control_characters_and_capped_in_length() {
+        let mut payload = payload_with(ExportedSecrets::default());
+        payload.settings.global_ollama.base_url =
+            Some(format!("http://example.test/{}\u{0007}bell", "x".repeat(200)));
+
+        let preview = SettingsImportPreview::from_payload(&payload);
+        let shown = preview.ollama_base_url.expect("non-blank base url");
+        assert!(!shown.contains('\u{0007}'), "control character leaked into the preview");
+        // +1 for the trailing ellipsis appended when truncated.
+        assert!(
+            shown.chars().count() <= MAX_PREVIEW_STRING_LEN + 1,
+            "preview string was not capped: {} chars",
+            shown.chars().count()
+        );
+    }
+}
diff --git a/app/src-tauri/src/storage/mod.rs b/app/src-tauri/src/storage/mod.rs
index 151759b..fda731f 100644
--- a/app/src-tauri/src/storage/mod.rs
+++ b/app/src-tauri/src/storage/mod.rs
@@ -2,6 +2,7 @@ pub mod migration_store;
 pub mod pending_cleanup;
 pub mod projects_store;
 pub mod secure;
+pub mod settings_crypto;
 pub mod settings_store;
 
 #[allow(unused_imports)]
diff --git a/app/src-tauri/src/storage/secure.rs b/app/src-tauri/src/storage/secure.rs
index a1c7e86..081dbf6 100644
--- a/app/src-tauri/src/storage/secure.rs
+++ b/app/src-tauri/src/storage/secure.rs
@@ -321,28 +321,52 @@ pub fn delete_gateway_api_key() -> Result<(), String> {
 /// only enforces auth when a master key is configured, so Triple-C always
 /// configures one.
 pub fn get_or_create_gateway_master_key() -> Result<String, String> {
-    if let Some(existing) = read_entry(GATEWAY_MASTER_KEY_SERVICE, "the gateway master key")? {
-        if !existing.trim().is_empty() {
-            return Ok(existing);
-        }
+    if let Some(existing) = get_gateway_master_key()? {
+        return Ok(existing);
     }
     regenerate_gateway_master_key()
 }
 
+/// Read the gateway master key without minting one if none exists yet.
+/// Distinct from [`get_or_create_gateway_master_key`], which mints as a side
+/// effect the read half of that function must not have — settings export
+/// (triple-c#35) needs "is there one, and if so what is it", not "make sure
+/// one exists".
+pub fn get_gateway_master_key() -> Result<Option<String>, String> {
+    Ok(read_entry(GATEWAY_MASTER_KEY_SERVICE, "the gateway master key")?
+        .filter(|k| !k.trim().is_empty()))
+}
+
 /// Mint a new gateway master key, invalidating the old one. Projects using the
 /// previous value must be updated.
 pub fn regenerate_gateway_master_key() -> Result<String, String> {
     // LiteLLM requires the master key to start with `sk-`.
     let key = format!("sk-triple-c-{}", uuid::Uuid::new_v4().simple());
+    store_gateway_master_key(&key)?;
+    Ok(key)
+}
+
+/// Store an exact given gateway master key, replacing any previous one.
+///
+/// Distinct from [`regenerate_gateway_master_key`], which always mints a
+/// fresh random value: this exists for settings import (triple-c#35), where
+/// restoring the *same* key an export captured is the point — projects on
+/// the destination machine may not exist yet, but a project migrated or
+/// re-added later that still has the old key pasted into its config must
+/// keep working against it. Blank input is rejected rather than silently
+/// stored, matching every other `store_*` function in this module.
+pub fn store_gateway_master_key(key: &str) -> Result<(), String> {
+    if key.trim().is_empty() {
+        return Err("Refusing to store an empty gateway master key.".to_string());
+    }
 
     let entry = keyring::Entry::new(GATEWAY_MASTER_KEY_SERVICE, KEYCHAIN_ACCOUNT)
         .map_err(|e| format!("Keyring error: {}", e))?;
     entry
-        .set_password(&key)
+        .set_password(key.trim())
         .map_err(|e| format!("Failed to store the gateway master key: {}", e))?;
 
-    bump_gateway_secret_version()?;
-    Ok(key)
+    bump_gateway_secret_version()
 }
 
 
diff --git a/app/src-tauri/src/storage/settings_crypto.rs b/app/src-tauri/src/storage/settings_crypto.rs
new file mode 100644
index 0000000..385edf1
--- /dev/null
+++ b/app/src-tauri/src/storage/settings_crypto.rs
@@ -0,0 +1,184 @@
+//! Password-based encryption for the settings export/import file — see
+//! triple-c#35.
+//!
+//! The exported payload can carry live credentials (the shared Claude OAuth
+//! token, the gateway provider/master keys — see
+//! `commands::settings_export_commands`), so this is not encryption for its
+//! own sake; a wrong or missing key here is a real credential leak, not a
+//! cosmetic bug. Argon2id derives a 256-bit key from the password (memory-
+//! hard, meaningfully resistant to GPU/ASIC brute-forcing in a way PBKDF2 at
+//! any reasonable iteration count is not), and AES-256-GCM is what actually
+//! encrypts — authenticated, so a wrong password is detected by a failed tag
+//! check rather than producing silent garbage.
+//!
+//! File format: `MAGIC (4 bytes) | salt (16 bytes) | nonce (12 bytes) |
+//! ciphertext+tag`. The salt and nonce are not secret — they are written in
+//! the clear right here, on purpose. The salt's only job is to make two
+//! exports with the same password derive different keys (defeats a
+//! precomputed-table attack against the password alone); the nonce's job is
+//! GCM's requirement that a (key, nonce) pair never repeat. Both hold
+//! because a fresh random value is drawn for each, on every call to
+//! [`encrypt`].
+//!
+//! The whole header (magic + salt + nonce) is passed to AES-GCM as
+//! associated data, not just placed alongside the ciphertext — free to do,
+//! and it makes tampering with any header byte fail the same authentication
+//! check the ciphertext gets, by construction rather than as a side effect
+//! of the salt/nonce also feeding key derivation and the cipher.
+
+use aes_gcm::aead::{Aead, KeyInit, Payload};
+use aes_gcm::{Aes256Gcm, Nonce};
+use argon2::{Algorithm, Argon2, Params, Version};
+use rand::RngCore;
+use zeroize::Zeroizing;
+
+/// Identifies the file as a Triple-C settings export and pins the format —
+/// a change to the salt/nonce lengths or the KDF/cipher choice below needs a
+/// new magic value, not a silent reinterpretation of old bytes.
+const MAGIC: &[u8; 4] = b"TCX1";
+const SALT_LEN: usize = 16;
+const NONCE_LEN: usize = 12;
+const KEY_LEN: usize = 32;
+const HEADER_LEN: usize = MAGIC.len() + SALT_LEN + NONCE_LEN;
+
+/// Argon2id parameters: memory cost in KiB, time cost (iterations),
+/// parallelism. `(19 MiB, 2, 1)` is OWASP's documented minimum recommendation
+/// for Argon2id — deliberately heavier than a login-flow KDF would use, since
+/// this runs once per export/import rather than on every request, so trading
+/// roughly a second of wall time for real brute-force resistance costs
+/// nothing a user would notice.
+fn argon2_params() -> Params {
+    Params::new(19 * 1024, 2, 1, Some(KEY_LEN)).expect("hardcoded Argon2 params are valid")
+}
+
+/// The derived key is wrapped in `Zeroizing` so it is overwritten with zeros
+/// when it drops rather than left in freed memory for whatever reuses that
+/// stack slot next — cheap insurance (`zeroize` is already in the dependency
+/// tree via `aes-gcm`) for material that exists only to decrypt live
+/// credentials.
+fn derive_key(password: &str, salt: &[u8]) -> Result<Zeroizing<[u8; KEY_LEN]>, String> {
+    let argon2 = Argon2::new(Algorithm::Argon2id, Version::V0x13, argon2_params());
+    let mut key = Zeroizing::new([0u8; KEY_LEN]);
+    argon2
+        .hash_password_into(password.as_bytes(), salt, &mut *key)
+        .map_err(|e| format!("Failed to derive encryption key: {}", e))?;
+    Ok(key)
+}
+
+/// Encrypt `plaintext` with a key derived from `password`. Returns the whole
+/// file's bytes (header + ciphertext) — see the module doc for the layout.
+pub fn encrypt(plaintext: &[u8], password: &str) -> Result<Vec<u8>, String> {
+    let mut salt = [0u8; SALT_LEN];
+    rand::rng().fill_bytes(&mut salt);
+    let key = derive_key(password, &salt)?;
+
+    let mut nonce_bytes = [0u8; NONCE_LEN];
+    rand::rng().fill_bytes(&mut nonce_bytes);
+    let nonce = Nonce::from_slice(&nonce_bytes);
+
+    let mut header = Vec::with_capacity(HEADER_LEN);
+    header.extend_from_slice(MAGIC);
+    header.extend_from_slice(&salt);
+    header.extend_from_slice(&nonce_bytes);
+
+    let cipher = Aes256Gcm::new_from_slice(&*key)
+        .map_err(|e| format!("Failed to initialize cipher: {}", e))?;
+    // The header (magic + salt + nonce) is authenticated as associated data
+    // even though none of it is secret: it costs nothing extra here, and it
+    // means tampering with any header byte is caught by the same tag check
+    // that already covers the ciphertext, by construction rather than as a
+    // side effect of the header also feeding key/nonce derivation.
+    let ciphertext = cipher
+        .encrypt(nonce, Payload { msg: plaintext, aad: &header })
+        .map_err(|e| format!("Encryption failed: {}", e))?;
+
+    let mut out = header;
+    out.extend_from_slice(&ciphertext);
+    Ok(out)
+}
+
+/// Decrypt a file produced by [`encrypt`]. The one error this returns for a
+/// wrong password is deliberately generic ("wrong password, or the file is
+/// corrupted") rather than distinguishing the two: GCM's authentication tag
+/// fails to verify for the wrong key on essentially any ciphertext, so there
+/// is no reliable way to tell "wrong password" from "corrupted file" apart,
+/// and guessing would be worse than saying so.
+///
+/// Returns `Zeroizing<Vec<u8>>` rather than a plain `Vec<u8>` — the plaintext
+/// this recovers is the whole settings-plus-secrets payload, so it gets the
+/// same "wipe it when it drops" treatment as the derived key in
+/// [`derive_key`].
+pub fn decrypt(data: &[u8], password: &str) -> Result<Zeroizing<Vec<u8>>, String> {
+    if data.len() < HEADER_LEN {
+        return Err("This does not look like a Triple-C settings export (file too short).".to_string());
+    }
+    if &data[..MAGIC.len()] != MAGIC {
+        return Err("This does not look like a Triple-C settings export (unrecognized file).".to_string());
+    }
+    let header = &data[..HEADER_LEN];
+    let salt = &data[MAGIC.len()..MAGIC.len() + SALT_LEN];
+    let nonce_bytes = &data[MAGIC.len() + SALT_LEN..HEADER_LEN];
+    let ciphertext = &data[HEADER_LEN..];
+
+    let key = derive_key(password, salt)?;
+    let cipher = Aes256Gcm::new_from_slice(&*key)
+        .map_err(|e| format!("Failed to initialize cipher: {}", e))?;
+    let nonce = Nonce::from_slice(nonce_bytes);
+    cipher
+        .decrypt(nonce, Payload { msg: ciphertext, aad: header })
+        .map(Zeroizing::new)
+        .map_err(|_| "Wrong password, or the file is corrupted.".to_string())
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn a_round_trip_with_the_right_password_recovers_the_plaintext() {
+        let plaintext = b"{\"settings\": \"whatever\"}";
+        let encrypted = encrypt(plaintext, "correct horse battery staple").unwrap();
+        let decrypted = decrypt(&encrypted, "correct horse battery staple").unwrap();
+        assert_eq!(&*decrypted, plaintext);
+    }
+
+    #[test]
+    fn the_wrong_password_fails_rather_than_returning_garbage() {
+        let encrypted = encrypt(b"secret payload", "correct password").unwrap();
+        let result = decrypt(&encrypted, "wrong password");
+        assert!(result.is_err(), "decrypting with the wrong password must fail, not silently succeed");
+    }
+
+    #[test]
+    fn two_exports_of_the_same_plaintext_and_password_produce_different_files() {
+        // If this ever failed it would mean the salt or nonce stopped being
+        // randomized — either one repeating is a real security regression
+        // (a fixed salt lets an attacker precompute against the password
+        // alone; a repeated (key, nonce) pair breaks GCM's guarantees
+        // outright), not just a cosmetic one.
+        let a = encrypt(b"same plaintext", "same password").unwrap();
+        let b = encrypt(b"same plaintext", "same password").unwrap();
+        assert_ne!(a, b, "two independent exports must not be byte-identical");
+    }
+
+    #[test]
+    fn corrupting_a_single_byte_of_ciphertext_is_detected() {
+        let mut encrypted = encrypt(b"tamper-evident payload", "a password").unwrap();
+        let last = encrypted.len() - 1;
+        encrypted[last] ^= 0xFF;
+        assert!(decrypt(&encrypted, "a password").is_err());
+    }
+
+    #[test]
+    fn a_file_that_is_too_short_is_rejected_cleanly_not_by_panicking() {
+        assert!(decrypt(b"short", "any password").is_err());
+        assert!(decrypt(b"", "any password").is_err());
+    }
+
+    #[test]
+    fn a_file_with_the_wrong_magic_is_rejected() {
+        let mut encrypted = encrypt(b"payload", "password").unwrap();
+        encrypted[0] = b'X';
+        assert!(decrypt(&encrypted, "password").is_err());
+    }
+}
diff --git a/app/src/components/settings/ExportSettingsModal.test.tsx b/app/src/components/settings/ExportSettingsModal.test.tsx
new file mode 100644
index 0000000..c8e85f7
--- /dev/null
+++ b/app/src/components/settings/ExportSettingsModal.test.tsx
@@ -0,0 +1,72 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { fireEvent, render, screen, waitFor } from "@testing-library/react";
+import ExportSettingsModal from "./ExportSettingsModal";
+
+const exportSettings = vi.fn();
+
+vi.mock("../../lib/tauri-commands", () => ({
+  exportSettings: (password: string) => exportSettings(password),
+}));
+
+beforeEach(() => {
+  vi.clearAllMocks();
+});
+
+function fillPasswords(password: string, confirm: string) {
+  fireEvent.change(screen.getByLabelText("Password"), { target: { value: password } });
+  fireEvent.change(screen.getByLabelText("Confirm password"), { target: { value: confirm } });
+}
+
+describe("ExportSettingsModal", () => {
+  it("keeps the submit button disabled until the passwords are long enough and match", () => {
+    render(<ExportSettingsModal onClose={vi.fn()} />);
+    const submit = screen.getByRole("button", { name: /choose where to save/i });
+    expect(submit).toBeDisabled();
+
+    fillPasswords("short", "short");
+    expect(submit).toBeDisabled();
+    expect(screen.getByText(/use at least 8 characters/i)).toBeInTheDocument();
+
+    fillPasswords("longenoughpassword", "different");
+    expect(submit).toBeDisabled();
+    expect(screen.getByText(/don't match/i)).toBeInTheDocument();
+
+    fillPasswords("longenoughpassword", "longenoughpassword");
+    expect(submit).not.toBeDisabled();
+  });
+
+  it("exports with the entered password and shows success", async () => {
+    exportSettings.mockResolvedValue(true);
+    render(<ExportSettingsModal onClose={vi.fn()} />);
+
+    fillPasswords("longenoughpassword", "longenoughpassword");
+    fireEvent.click(screen.getByRole("button", { name: /choose where to save/i }));
+
+    await waitFor(() => expect(exportSettings).toHaveBeenCalledWith("longenoughpassword"));
+    await waitFor(() => expect(screen.getByText(/settings exported/i)).toBeInTheDocument());
+  });
+
+  it("closes quietly when the save dialog is dismissed", async () => {
+    exportSettings.mockResolvedValue(false);
+    const onClose = vi.fn();
+    render(<ExportSettingsModal onClose={onClose} />);
+
+    fillPasswords("longenoughpassword", "longenoughpassword");
+    fireEvent.click(screen.getByRole("button", { name: /choose where to save/i }));
+
+    await waitFor(() => expect(onClose).toHaveBeenCalled());
+    expect(screen.queryByText(/settings exported/i)).not.toBeInTheDocument();
+  });
+
+  it("shows an error rather than closing when the export fails", async () => {
+    exportSettings.mockRejectedValue("Disk is full");
+    const onClose = vi.fn();
+    render(<ExportSettingsModal onClose={onClose} />);
+
+    fillPasswords("longenoughpassword", "longenoughpassword");
+    fireEvent.click(screen.getByRole("button", { name: /choose where to save/i }));
+
+    await waitFor(() => expect(screen.getByText("Disk is full")).toBeInTheDocument());
+    expect(onClose).not.toHaveBeenCalled();
+  });
+});
diff --git a/app/src/components/settings/ExportSettingsModal.tsx b/app/src/components/settings/ExportSettingsModal.tsx
new file mode 100644
index 0000000..cd1d70a
--- /dev/null
+++ b/app/src/components/settings/ExportSettingsModal.tsx
@@ -0,0 +1,119 @@
+import { useState } from "react";
+import Modal from "../ui/Modal";
+import Button from "../ui/Button";
+import Field, { inputClass } from "../ui/Field";
+import { exportSettings } from "../../lib/tauri-commands";
+
+interface Props {
+  onClose: () => void;
+}
+
+const MIN_PASSWORD_LENGTH = 8;
+
+/**
+ * Password entry for exporting global settings. The save dialog itself opens
+ * from Rust once a password is confirmed here — see the doc comment on
+ * `commands::settings_export_commands` for why the host path never
+ * round-trips through this component.
+ */
+export default function ExportSettingsModal({ onClose }: Props) {
+  const [password, setPassword] = useState("");
+  const [confirmPassword, setConfirmPassword] = useState("");
+  const [busy, setBusy] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+  const [done, setDone] = useState(false);
+
+  const mismatch = confirmPassword.length > 0 && password !== confirmPassword;
+  const tooShort = password.length > 0 && password.length < MIN_PASSWORD_LENGTH;
+  const canSubmit = password.length >= MIN_PASSWORD_LENGTH && password === confirmPassword;
+
+  const handleExport = async () => {
+    setError(null);
+    setBusy(true);
+    try {
+      const saved = await exportSettings(password);
+      if (saved) setDone(true);
+      // `false` means the save dialog was dismissed — close quietly, same as
+      // if the user had cancelled the modal itself.
+      else onClose();
+    } catch (e) {
+      setError(String(e));
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  return (
+    <Modal
+      title="Export settings"
+      description="Saves your global settings and any stored credentials (a shared Claude login, gateway keys) to one encrypted file. Project-specific settings and container data are not included."
+      widthClassName="w-[28rem]"
+      dismissible={!busy}
+      onClose={onClose}
+      footer={
+        done ? (
+          <Button size="md" variant="primary" onClick={onClose}>
+            Done
+          </Button>
+        ) : (
+          <>
+            <Button size="md" variant="ghost" onClick={onClose} disabled={busy}>
+              Cancel
+            </Button>
+            <Button
+              size="md"
+              variant="primary"
+              onClick={() => void handleExport()}
+              disabled={!canSubmit || busy}
+            >
+              {busy ? "Exporting…" : "Choose where to save…"}
+            </Button>
+          </>
+        )
+      }
+    >
+      {done ? (
+        <p className="text-[13px] text-[var(--success)]">
+          Settings exported. Keep the password somewhere safe — there is no way to recover
+          the file without it.
+        </p>
+      ) : (
+        <div className="space-y-3">
+          <Field label="Password" hint={`At least ${MIN_PASSWORD_LENGTH} characters. You'll need this exact password to import the file later.`}>
+            {(id) => (
+              <input
+                id={id}
+                type="password"
+                autoComplete="new-password"
+                value={password}
+                onChange={(e) => setPassword(e.target.value)}
+                disabled={busy}
+                className={inputClass}
+              />
+            )}
+          </Field>
+          <Field label="Confirm password">
+            {(id) => (
+              <input
+                id={id}
+                type="password"
+                autoComplete="new-password"
+                value={confirmPassword}
+                onChange={(e) => setConfirmPassword(e.target.value)}
+                disabled={busy}
+                className={inputClass}
+              />
+            )}
+          </Field>
+          {tooShort && (
+            <p className="text-xs text-[var(--error)]">
+              Use at least {MIN_PASSWORD_LENGTH} characters.
+            </p>
+          )}
+          {mismatch && <p className="text-xs text-[var(--error)]">Passwords don't match.</p>}
+          {error && <p className="text-xs text-[var(--error)]">{error}</p>}
+        </div>
+      )}
+    </Modal>
+  );
+}
diff --git a/app/src/components/settings/ImportSettingsModal.test.tsx b/app/src/components/settings/ImportSettingsModal.test.tsx
new file mode 100644
index 0000000..9a56f02
--- /dev/null
+++ b/app/src/components/settings/ImportSettingsModal.test.tsx
@@ -0,0 +1,145 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { fireEvent, render, screen, waitFor } from "@testing-library/react";
+import ImportSettingsModal from "./ImportSettingsModal";
+import type { AppSettings, SettingsImportOutcome, SettingsImportPreview } from "../../lib/types";
+
+const previewSettingsImport = vi.fn();
+const applySettingsImport = vi.fn();
+
+vi.mock("../../lib/tauri-commands", () => ({
+  previewSettingsImport: (password: string) => previewSettingsImport(password),
+  applySettingsImport: (password: string) => applySettingsImport(password),
+}));
+
+beforeEach(() => {
+  vi.clearAllMocks();
+});
+
+const samplePreview: SettingsImportPreview = {
+  exported_at: "2026-08-27T00:00:00Z",
+  app_version: "0.4.14",
+  custom_env_var_count: 2,
+  gateway_model_count: 0,
+  has_claude_code_settings: false,
+  has_claude_oauth_token: true,
+  has_gateway_api_key: false,
+  has_gateway_master_key: false,
+  has_web_terminal_access_token: false,
+  enables_web_terminal: false,
+  ollama_base_url: null,
+  llamacpp_base_url: null,
+  openai_compatible_base_url: null,
+  gateway_api_base: null,
+  image_source: "registry",
+  custom_image_name: null,
+};
+
+function outcome(settings: AppSettings, secretRestoreWarnings: string[] = []): SettingsImportOutcome {
+  return { settings, secret_restore_warnings: secretRestoreWarnings };
+}
+
+describe("ImportSettingsModal", () => {
+  it("keeps 'Choose file' disabled until a password is entered", () => {
+    render(<ImportSettingsModal onClose={vi.fn()} onImported={vi.fn()} />);
+    expect(screen.getByRole("button", { name: /choose file/i })).toBeDisabled();
+
+    fireEvent.change(screen.getByLabelText("Password"), { target: { value: "hunter2" } });
+    expect(screen.getByRole("button", { name: /choose file/i })).not.toBeDisabled();
+  });
+
+  it("shows the preview and confirms with the same password used to open it", async () => {
+    previewSettingsImport.mockResolvedValue(samplePreview);
+    applySettingsImport.mockResolvedValue(outcome({} as AppSettings));
+    const onImported = vi.fn();
+    render(<ImportSettingsModal onClose={vi.fn()} onImported={onImported} />);
+
+    fireEvent.change(screen.getByLabelText("Password"), { target: { value: "hunter2" } });
+    fireEvent.click(screen.getByRole("button", { name: /choose file/i }));
+
+    await waitFor(() => expect(previewSettingsImport).toHaveBeenCalledWith("hunter2"));
+    expect(await screen.findByText(/2 global custom env vars/i)).toBeInTheDocument();
+    expect(screen.getByText(/your shared claude login/i)).toBeInTheDocument();
+
+    fireEvent.click(screen.getByRole("button", { name: /^import$/i }));
+    await waitFor(() => expect(applySettingsImport).toHaveBeenCalledWith("hunter2"));
+    await waitFor(() => expect(onImported).toHaveBeenCalledWith({}));
+    expect(await screen.findByText(/settings imported/i)).toBeInTheDocument();
+  });
+
+  it("shows a distinct warning when the import would enable the web terminal", async () => {
+    previewSettingsImport.mockResolvedValue({ ...samplePreview, enables_web_terminal: true });
+    render(<ImportSettingsModal onClose={vi.fn()} onImported={vi.fn()} />);
+
+    fireEvent.change(screen.getByLabelText("Password"), { target: { value: "hunter2" } });
+    fireEvent.click(screen.getByRole("button", { name: /choose file/i }));
+
+    expect(await screen.findByText(/enables the remote web terminal/i)).toBeInTheDocument();
+  });
+
+  it("warns about a custom Docker image every time, not just on change", async () => {
+    previewSettingsImport.mockResolvedValue({
+      ...samplePreview,
+      image_source: "custom",
+      custom_image_name: "ghcr.io/attacker/triple-c:latest",
+    });
+    render(<ImportSettingsModal onClose={vi.fn()} onImported={vi.fn()} />);
+
+    fireEvent.change(screen.getByLabelText("Password"), { target: { value: "hunter2" } });
+    fireEvent.click(screen.getByRole("button", { name: /choose file/i }));
+
+    expect(
+      await screen.findByText(/custom docker image: ghcr\.io\/attacker\/triple-c:latest/i),
+    ).toBeInTheDocument();
+  });
+
+  it("shows a secret-restore warning alongside success rather than hiding it", async () => {
+    previewSettingsImport.mockResolvedValue(samplePreview);
+    applySettingsImport.mockResolvedValue(
+      outcome({} as AppSettings, ["Could not restore the gateway master key: keychain locked"]),
+    );
+    render(<ImportSettingsModal onClose={vi.fn()} onImported={vi.fn()} />);
+
+    fireEvent.change(screen.getByLabelText("Password"), { target: { value: "hunter2" } });
+    fireEvent.click(screen.getByRole("button", { name: /choose file/i }));
+    await screen.findByText(/2 global custom env vars/i);
+
+    fireEvent.click(screen.getByRole("button", { name: /^import$/i }));
+    expect(await screen.findByText(/settings imported/i)).toBeInTheDocument();
+    expect(await screen.findByText(/could not restore the gateway master key/i)).toBeInTheDocument();
+  });
+
+  it("closes quietly when the file picker is dismissed", async () => {
+    previewSettingsImport.mockResolvedValue(null);
+    const onClose = vi.fn();
+    render(<ImportSettingsModal onClose={onClose} onImported={vi.fn()} />);
+
+    fireEvent.change(screen.getByLabelText("Password"), { target: { value: "hunter2" } });
+    fireEvent.click(screen.getByRole("button", { name: /choose file/i }));
+
+    await waitFor(() => expect(onClose).toHaveBeenCalled());
+  });
+
+  it("shows an error when the password is wrong rather than a blank preview", async () => {
+    previewSettingsImport.mockRejectedValue("Wrong password, or the file is corrupted.");
+    render(<ImportSettingsModal onClose={vi.fn()} onImported={vi.fn()} />);
+
+    fireEvent.change(screen.getByLabelText("Password"), { target: { value: "wrong" } });
+    fireEvent.click(screen.getByRole("button", { name: /choose file/i }));
+
+    expect(await screen.findByText(/wrong password, or the file is corrupted/i)).toBeInTheDocument();
+  });
+
+  it("shows an error if applying the import fails, without claiming success", async () => {
+    previewSettingsImport.mockResolvedValue(samplePreview);
+    applySettingsImport.mockRejectedValue("Keychain write failed");
+    render(<ImportSettingsModal onClose={vi.fn()} onImported={vi.fn()} />);
+
+    fireEvent.change(screen.getByLabelText("Password"), { target: { value: "hunter2" } });
+    fireEvent.click(screen.getByRole("button", { name: /choose file/i }));
+    await screen.findByText(/2 global custom env vars/i);
+
+    fireEvent.click(screen.getByRole("button", { name: /^import$/i }));
+    expect(await screen.findByText("Keychain write failed")).toBeInTheDocument();
+    expect(screen.queryByText(/settings imported/i)).not.toBeInTheDocument();
+  });
+});
diff --git a/app/src/components/settings/ImportSettingsModal.tsx b/app/src/components/settings/ImportSettingsModal.tsx
new file mode 100644
index 0000000..c914c3b
--- /dev/null
+++ b/app/src/components/settings/ImportSettingsModal.tsx
@@ -0,0 +1,166 @@
+import { useState } from "react";
+import Modal from "../ui/Modal";
+import Button from "../ui/Button";
+import Field, { inputClass } from "../ui/Field";
+import { applySettingsImport, previewSettingsImport } from "../../lib/tauri-commands";
+import { describeImport, describeImportWarnings } from "../../lib/settingsImportPreview";
+import type { AppSettings, SettingsImportPreview } from "../../lib/types";
+
+interface Props {
+  onClose: () => void;
+  /** Fired once the import is actually applied, so the caller can refresh
+   *  whatever reads settings from the store. */
+  onImported: (settings: AppSettings) => void;
+}
+
+/**
+ * Two phases: enter the password and pick the file (backend resolves the
+ * file dialog itself — see `commands::settings_export_commands`), then
+ * confirm a preview before anything is actually applied. The same password
+ * is reused for the second call rather than asking again; nothing about
+ * that call needs a fresh secret; the backend just doesn't cache the
+ * *decrypted payload* between the two.
+ */
+export default function ImportSettingsModal({ onClose, onImported }: Props) {
+  const [password, setPassword] = useState("");
+  const [busy, setBusy] = useState(false);
+  const [error, setError] = useState<string | null>(null);
+  const [preview, setPreview] = useState<SettingsImportPreview | null>(null);
+  const [applied, setApplied] = useState(false);
+  const [secretWarnings, setSecretWarnings] = useState<string[]>([]);
+
+  const handleChooseFile = async () => {
+    setError(null);
+    setBusy(true);
+    try {
+      const result = await previewSettingsImport(password);
+      if (result) setPreview(result);
+      else onClose(); // File picker dismissed.
+    } catch (e) {
+      setError(String(e));
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  const handleConfirm = async () => {
+    setError(null);
+    setBusy(true);
+    try {
+      const outcome = await applySettingsImport(password);
+      setApplied(true);
+      setSecretWarnings(outcome.secret_restore_warnings);
+      onImported(outcome.settings);
+    } catch (e) {
+      setError(String(e));
+    } finally {
+      setBusy(false);
+    }
+  };
+
+  return (
+    <Modal
+      title="Import settings"
+      description={
+        preview
+          ? "Review what this file will change before applying it."
+          : "Choose a Triple-C settings export and enter the password it was created with."
+      }
+      widthClassName="w-[28rem]"
+      dismissible={!busy}
+      onClose={onClose}
+      footer={
+        applied ? (
+          <Button size="md" variant="primary" onClick={onClose}>
+            Done
+          </Button>
+        ) : preview ? (
+          <>
+            <Button size="md" variant="ghost" onClick={onClose} disabled={busy}>
+              Cancel
+            </Button>
+            <Button size="md" variant="primary" onClick={() => void handleConfirm()} disabled={busy}>
+              {busy ? "Importing…" : "Import"}
+            </Button>
+          </>
+        ) : (
+          <>
+            <Button size="md" variant="ghost" onClick={onClose} disabled={busy}>
+              Cancel
+            </Button>
+            <Button
+              size="md"
+              variant="primary"
+              onClick={() => void handleChooseFile()}
+              disabled={!password || busy}
+            >
+              {busy ? "Opening…" : "Choose file…"}
+            </Button>
+          </>
+        )
+      }
+    >
+      {applied ? (
+        <div className="space-y-2">
+          <p className="text-[13px] text-[var(--success)]">Settings imported.</p>
+          {secretWarnings.map((warning) => (
+            <p
+              key={warning}
+              className="px-2.5 py-2 text-xs text-[var(--error)] bg-[var(--error-muted)] border border-[var(--error)]/40 rounded-[var(--radius-control)] leading-snug"
+            >
+              {warning}
+            </p>
+          ))}
+        </div>
+      ) : preview ? (
+        <div className="space-y-3">
+          <p className="text-xs text-[var(--text-secondary)]">
+            Exported {new Date(preview.exported_at).toLocaleString()} from Triple-C{" "}
+            {preview.app_version}.
+          </p>
+          {/* Warnings render before the replace list, deliberately: the list
+           *  below can run long, and the one thing here that most needs to
+           *  stay above the fold while scrolling is "this turns on a
+           *  network-listening service" or "this runs a different image" —
+           *  not a bullet buried among ordinary settings. */}
+          {describeImportWarnings(preview).map((warning) => (
+            <p
+              key={warning}
+              className="px-2.5 py-2 text-xs text-[var(--warning)] bg-[var(--warning-muted)] border border-[var(--warning)]/40 rounded-[var(--radius-control)] leading-snug break-all"
+            >
+              {warning}
+            </p>
+          ))}
+          <div>
+            <p className="text-[13px] font-medium text-[var(--text-primary)]">This will replace:</p>
+            <ul className="mt-1 list-disc pl-4 text-[13px] text-[var(--text-secondary)] space-y-0.5">
+              {describeImport(preview).map((item) => (
+                <li key={item} className="break-all">
+                  {item}
+                </li>
+              ))}
+            </ul>
+          </div>
+          {error && <p className="text-xs text-[var(--error)]">{error}</p>}
+        </div>
+      ) : (
+        <div className="space-y-3">
+          <Field label="Password">
+            {(id) => (
+              <input
+                id={id}
+                type="password"
+                autoComplete="current-password"
+                value={password}
+                onChange={(e) => setPassword(e.target.value)}
+                disabled={busy}
+                className={inputClass}
+              />
+            )}
+          </Field>
+          {error && <p className="text-xs text-[var(--error)]">{error}</p>}
+        </div>
+      )}
+    </Modal>
+  );
+}
diff --git a/app/src/components/settings/SettingsPanel.tsx b/app/src/components/settings/SettingsPanel.tsx
index 062a9f4..ea11494 100644
--- a/app/src/components/settings/SettingsPanel.tsx
+++ b/app/src/components/settings/SettingsPanel.tsx
@@ -19,9 +19,11 @@ import WebTerminalSettings from "./WebTerminalSettings";
 import SttSettings from "./SttSettings";
 import SharedAuthSettings from "./SharedAuthSettings";
 import CertificateSettings from "./CertificateSettings";
+import ExportSettingsModal from "./ExportSettingsModal";
+import ImportSettingsModal from "./ImportSettingsModal";
 
 export default function SettingsPanel() {
-  const { appSettings, saveSettings } = useSettings();
+  const { appSettings, saveSettings, setAppSettings } = useSettings();
   const { appVersion, imageUpdateInfo, checkForUpdates, checkImageUpdate } = useUpdates();
   const [globalInstructions, setGlobalInstructions] = useState(appSettings?.global_claude_instructions ?? "");
   const [globalEnvVars, setGlobalEnvVars] = useState<EnvVar[]>(appSettings?.global_custom_env_vars ?? []);
@@ -33,6 +35,8 @@ export default function SettingsPanel() {
   const [showInstructionsModal, setShowInstructionsModal] = useState(false);
   const [showEnvVarsModal, setShowEnvVarsModal] = useState(false);
   const [showClaudeCodeSettingsModal, setShowClaudeCodeSettingsModal] = useState(false);
+  const [showExportModal, setShowExportModal] = useState(false);
+  const [showImportModal, setShowImportModal] = useState(false);
 
   // Sync local state when appSettings change
   useEffect(() => {
@@ -269,6 +273,39 @@ export default function SettingsPanel() {
         </div>
       </AccordionSection>
 
+      <AccordionSection id="backup" title="Backup" defaultOpen={false}>
+        <div className="space-y-2">
+          <p className="text-xs text-[var(--text-secondary)] leading-snug">
+            Export your global settings and stored credentials (a shared Claude login,
+            gateway keys) to one password-encrypted file, or restore them on a new machine.
+            Project-specific settings and container data are never included.
+          </p>
+          <div className="flex gap-2">
+            <button
+              onClick={() => setShowExportModal(true)}
+              className="px-3 py-1.5 text-xs bg-[var(--bg-primary)] border border-[var(--border-color)] rounded hover:bg-[var(--border-color)] transition-colors"
+            >
+              Export settings…
+            </button>
+            <button
+              onClick={() => setShowImportModal(true)}
+              className="px-3 py-1.5 text-xs bg-[var(--bg-primary)] border border-[var(--border-color)] rounded hover:bg-[var(--border-color)] transition-colors"
+            >
+              Import settings…
+            </button>
+          </div>
+        </div>
+      </AccordionSection>
+
+      {showExportModal && <ExportSettingsModal onClose={() => setShowExportModal(false)} />}
+
+      {showImportModal && (
+        <ImportSettingsModal
+          onClose={() => setShowImportModal(false)}
+          onImported={(settings) => setAppSettings(settings)}
+        />
+      )}
+
       {showInstructionsModal && (
         <ClaudeInstructionsModal
           instructions={globalInstructions}
diff --git a/app/src/hooks/useSettings.ts b/app/src/hooks/useSettings.ts
index fb83d1a..01bf9d4 100644
--- a/app/src/hooks/useSettings.ts
+++ b/app/src/hooks/useSettings.ts
@@ -36,5 +36,9 @@ export function useSettings() {
     appSettings,
     loadSettings,
     saveSettings,
+    /** For a command that already returns the new `AppSettings` itself
+     *  (settings import) — updates the store without a redundant
+     *  `updateSettings` round trip through the backend. */
+    setAppSettings,
   };
 }
diff --git a/app/src/lib/settingsImportPreview.test.ts b/app/src/lib/settingsImportPreview.test.ts
new file mode 100644
index 0000000..aa94e9d
--- /dev/null
+++ b/app/src/lib/settingsImportPreview.test.ts
@@ -0,0 +1,125 @@
+import { describe, it, expect } from "vitest";
+import { describeImport, describeImportWarnings } from "./settingsImportPreview";
+import type { SettingsImportPreview } from "./types";
+
+function preview(overrides: Partial<SettingsImportPreview> = {}): SettingsImportPreview {
+  return {
+    exported_at: "2026-08-27T00:00:00Z",
+    app_version: "0.4.14",
+    custom_env_var_count: 0,
+    gateway_model_count: 0,
+    has_claude_code_settings: false,
+    has_claude_oauth_token: false,
+    has_gateway_api_key: false,
+    has_gateway_master_key: false,
+    has_web_terminal_access_token: false,
+    enables_web_terminal: false,
+    ollama_base_url: null,
+    llamacpp_base_url: null,
+    openai_compatible_base_url: null,
+    gateway_api_base: null,
+    image_source: "registry",
+    custom_image_name: null,
+    ...overrides,
+  };
+}
+
+describe("describeImport", () => {
+  it("always names the settings replacement, even with nothing else set", () => {
+    expect(describeImport(preview())).toEqual([
+      "Your global settings (all of them — this replaces what's here now)",
+    ]);
+  });
+
+  it("singularizes a count of exactly one", () => {
+    const items = describeImport(preview({ custom_env_var_count: 1, gateway_model_count: 1 }));
+    expect(items).toContain("1 global custom env var");
+    expect(items).toContain("1 gateway model");
+  });
+
+  it("pluralizes counts greater than one", () => {
+    const items = describeImport(preview({ custom_env_var_count: 3, gateway_model_count: 2 }));
+    expect(items).toContain("3 global custom env vars");
+    expect(items).toContain("2 gateway models");
+  });
+
+  it("names every present secret and setting without naming absent ones", () => {
+    const items = describeImport(
+      preview({
+        has_claude_code_settings: true,
+        has_claude_oauth_token: true,
+        has_gateway_api_key: true,
+        has_gateway_master_key: true,
+      }),
+    );
+    expect(items).toContain("Global Claude Code settings");
+    expect(items).toContain("Your shared Claude login");
+    expect(items).toContain("The gateway provider API key");
+    expect(items).toContain("The gateway master key");
+    // None of the count-based items, since both counts are 0.
+    expect(items.some((i) => i.includes("env var"))).toBe(false);
+    expect(items.some((i) => i.includes("gateway model"))).toBe(false);
+  });
+
+  it("names the web terminal access token like any other present secret", () => {
+    const items = describeImport(preview({ has_web_terminal_access_token: true }));
+    expect(items).toContain("The web terminal access token");
+  });
+
+  it("names custom base URLs verbatim, since they're endpoints rather than secrets", () => {
+    const items = describeImport(
+      preview({
+        ollama_base_url: "http://10.0.0.5:11434",
+        gateway_api_base: "https://gateway.example/v1",
+      }),
+    );
+    expect(items).toContain("Ollama server: http://10.0.0.5:11434");
+    expect(items).toContain("Gateway upstream: https://gateway.example/v1");
+    expect(items.some((i) => i.includes("llama.cpp"))).toBe(false);
+    expect(items.some((i) => i.includes("OpenAI-compatible"))).toBe(false);
+  });
+
+  it("names a custom Docker image when set, falling back to a placeholder if unnamed", () => {
+    expect(
+      describeImport(preview({ image_source: "custom", custom_image_name: "ghcr.io/me/triple-c" })),
+    ).toContain("Docker image: ghcr.io/me/triple-c");
+    expect(describeImport(preview({ image_source: "custom", custom_image_name: null }))).toContain(
+      "Docker image: (no image name set)",
+    );
+    expect(describeImport(preview({ image_source: "registry" })).some((i) => i.includes("Docker image"))).toBe(
+      false,
+    );
+  });
+});
+
+describe("describeImportWarnings", () => {
+  it("is empty when nothing about the import needs extra attention", () => {
+    expect(describeImportWarnings(preview())).toEqual([]);
+  });
+
+  it("warns when the import enables the web terminal, regardless of the token", () => {
+    // `enabled` and the token are independent — the warning is about the
+    // service turning on, whether or not a token came with it.
+    expect(describeImportWarnings(preview({ enables_web_terminal: true }))).toEqual([
+      "Enables the remote web terminal, which listens on your network.",
+    ]);
+    expect(
+      describeImportWarnings(
+        preview({ enables_web_terminal: true, has_web_terminal_access_token: true }),
+      ),
+    ).toHaveLength(1);
+  });
+
+  it("warns about a dormant web terminal token even while the terminal stays off", () => {
+    expect(describeImportWarnings(preview({ has_web_terminal_access_token: true }))).toEqual([
+      "Includes a web terminal access token that will activate the next time the web terminal is turned on.",
+    ]);
+  });
+
+  it("warns about a custom Docker image every time, not only when it changes", () => {
+    expect(
+      describeImportWarnings(preview({ image_source: "custom", custom_image_name: "evil:latest" })),
+    ).toEqual(["Runs every project container from a custom Docker image: evil:latest."]);
+    expect(describeImportWarnings(preview({ image_source: "registry" }))).toEqual([]);
+  });
+});
diff --git a/app/src/lib/settingsImportPreview.ts b/app/src/lib/settingsImportPreview.ts
new file mode 100644
index 0000000..c8e05e6
--- /dev/null
+++ b/app/src/lib/settingsImportPreview.ts
@@ -0,0 +1,67 @@
+import type { SettingsImportPreview } from "./types";
+
+/** Named things a `SettingsImportPreview` says an import will change, for
+ *  `ImportSettingsModal`'s confirmation list. Does not include anything
+ *  `describeImportWarnings` covers — those get their own, more visible
+ *  treatment rather than blending into this list. */
+export function describeImport(preview: SettingsImportPreview): string[] {
+  const items: string[] = ["Your global settings (all of them — this replaces what's here now)"];
+  if (preview.custom_env_var_count > 0) {
+    items.push(
+      `${preview.custom_env_var_count} global custom env var${preview.custom_env_var_count === 1 ? "" : "s"}`,
+    );
+  }
+  if (preview.has_claude_code_settings) items.push("Global Claude Code settings");
+  if (preview.gateway_model_count > 0) {
+    items.push(`${preview.gateway_model_count} gateway model${preview.gateway_model_count === 1 ? "" : "s"}`);
+  }
+  if (preview.has_claude_oauth_token) items.push("Your shared Claude login");
+  if (preview.has_gateway_api_key) items.push("The gateway provider API key");
+  if (preview.has_gateway_master_key) items.push("The gateway master key");
+  if (preview.has_web_terminal_access_token) items.push("The web terminal access token");
+  if (preview.ollama_base_url) items.push(`Ollama server: ${preview.ollama_base_url}`);
+  if (preview.llamacpp_base_url) items.push(`llama.cpp server: ${preview.llamacpp_base_url}`);
+  if (preview.openai_compatible_base_url) {
+    items.push(`OpenAI-compatible server: ${preview.openai_compatible_base_url}`);
+  }
+  if (preview.gateway_api_base) items.push(`Gateway upstream: ${preview.gateway_api_base}`);
+  if (preview.image_source === "custom") {
+    items.push(`Docker image: ${preview.custom_image_name ?? "(no image name set)"}`);
+  }
+  return items;
+}
+
+/**
+ * Things about an import that deserve more attention than a bullet in a
+ * long list — deliberately its own function rather than a flag inside
+ * `describeImport`: a setting that turns on a network-listening service is
+ * exactly the kind of change a "your settings were replaced" summary is bad
+ * at surfacing, on purpose or (if the file came from someone else) not.
+ *
+ * A token that arrives with the terminal left *off* gets its own warning
+ * too, distinct from the "enables it now" one: `start_web_terminal` only
+ * mints a fresh token when none is already set, so a planted token here
+ * would silently become live the next time someone flips the terminal on
+ * through the UI, with no import-time signal that it wasn't freshly
+ * generated.
+ *
+ * A custom Docker image gets a warning every time, not just on change: it's
+ * the image every project container is created from, so it's worth calling
+ * out regardless of what was configured before the import.
+ */
+export function describeImportWarnings(preview: SettingsImportPreview): string[] {
+  const warnings: string[] = [];
+  if (preview.enables_web_terminal) {
+    warnings.push("Enables the remote web terminal, which listens on your network.");
+  } else if (preview.has_web_terminal_access_token) {
+    warnings.push(
+      "Includes a web terminal access token that will activate the next time the web terminal is turned on.",
+    );
+  }
+  if (preview.image_source === "custom") {
+    warnings.push(
+      `Runs every project container from a custom Docker image: ${preview.custom_image_name ?? "(no image name set)"}.`,
+    );
+  }
+  return warnings;
+}
diff --git a/app/src/lib/tauri-commands.ts b/app/src/lib/tauri-commands.ts
index 6389a4c..c9a2b1f 100644
--- a/app/src/lib/tauri-commands.ts
+++ b/app/src/lib/tauri-commands.ts
@@ -1,5 +1,5 @@
 import { invoke } from "@tauri-apps/api/core";
-import type { Project, ProjectPath, ProjectRemovalReport, ProjectResetOutcome, ContainerInfo, AppSettings, UpdateInfo, ImageUpdateInfo, FileEntry, FileContents, WebTerminalInfo, SttStatus, GatewayStatus, InstallOptions, ClaudeSession, ContainerCapabilities, ScheduledTask, ScheduledTaskInput, SchedulerNotification, AuthBridgeStatus, BrowserViewStatus, BrowserViewPopoutState, BrowserPageState, PlaywrightDetection, BrowserSetupOutcome, BrowserInstallTarget, ContainerStaleness, MigrationOptions, MigrationReport, MigrationState, ClearTokenOutcome, CaCertInfo, UploadOutcome } from "./types";
+import type { Project, ProjectPath, ProjectRemovalReport, ProjectResetOutcome, ContainerInfo, AppSettings, SettingsImportPreview, SettingsImportOutcome, UpdateInfo, ImageUpdateInfo, FileEntry, FileContents, WebTerminalInfo, SttStatus, GatewayStatus, InstallOptions, ClaudeSession, ContainerCapabilities, ScheduledTask, ScheduledTaskInput, SchedulerNotification, AuthBridgeStatus, BrowserViewStatus, BrowserViewPopoutState, BrowserPageState, PlaywrightDetection, BrowserSetupOutcome, BrowserInstallTarget, ContainerStaleness, MigrationOptions, MigrationReport, MigrationState, ClearTokenOutcome, CaCertInfo, UploadOutcome } from "./types";
 
 // Docker
 export const checkDocker = () => invoke<boolean>("check_docker");
@@ -42,6 +42,15 @@ export const inspectCaCertPath = (path: string) =>
 export const detectHostTimezone = () =>
   invoke<string>("detect_host_timezone");
 
+// Settings export/import — `false`/`null` mean the save/open dialog was
+// dismissed, not an error.
+export const exportSettings = (password: string) =>
+  invoke<boolean>("export_settings", { password });
+export const previewSettingsImport = (password: string) =>
+  invoke<SettingsImportPreview | null>("preview_settings_import", { password });
+export const applySettingsImport = (password: string) =>
+  invoke<SettingsImportOutcome>("apply_settings_import", { password });
+
 // AWS
 export const awsSsoRefresh = (projectId: string) =>
   invoke<void>("aws_sso_refresh", { projectId });
diff --git a/app/src/lib/types.ts b/app/src/lib/types.ts
index 9a6462c..ae2250c 100644
--- a/app/src/lib/types.ts
+++ b/app/src/lib/types.ts
@@ -292,6 +292,46 @@ export interface AppSettings {
   global_claude_code_settings: ClaudeCodeSettings | null;
 }
 
+/** What `preview_settings_import` returns before anything is applied —
+ *  counts and presence flags only, never a secret value itself. Built from
+ *  this, not from the raw import file, which the frontend never sees. */
+export interface SettingsImportPreview {
+  exported_at: string;
+  app_version: string;
+  custom_env_var_count: number;
+  gateway_model_count: number;
+  has_claude_code_settings: boolean;
+  has_claude_oauth_token: boolean;
+  has_gateway_api_key: boolean;
+  has_gateway_master_key: boolean;
+  has_web_terminal_access_token: boolean;
+  /** Whether the import turns the web terminal on — surfaced separately
+   *  from the token above since either can be true without the other, and
+   *  "this enables a service that listens on your network" must not hide
+   *  inside a generic "settings replaced" summary. */
+  enables_web_terminal: boolean;
+  /** Non-blank custom base URLs the import would set — endpoints, not
+   *  secrets, so shown verbatim to disclose a redirect of model traffic. */
+  ollama_base_url: string | null;
+  llamacpp_base_url: string | null;
+  openai_compatible_base_url: string | null;
+  gateway_api_base: string | null;
+  /** Whether the import sets a custom Docker image, and its name if so —
+   *  this is the image every project container is created from, so worth
+   *  more attention than an ordinary setting. */
+  image_source: ImageSource;
+  custom_image_name: string | null;
+}
+
+/** What `apply_settings_import` returns: the settings that were actually
+ *  saved, plus a note for each keychain secret the import carried but could
+ *  not be restored (a partial keychain failure must not read as unqualified
+ *  success just because the settings half went through). */
+export interface SettingsImportOutcome {
+  settings: AppSettings;
+  secret_restore_warnings: string[];
+}
+
 /** What `inspect_ca_cert_path` reports about a corporate CA path. Errors ride
  *  in the payload rather than rejecting, so the field can render them inline
  *  while the user is still typing. */