Triple-C/CLAUDE.md

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

Triple-C (Claude-Code-Container) is a Tauri v2 desktop application that sandboxes Claude Code inside Docker containers. It has two main parts: a React/TypeScript frontend, a Rust backend, and a Docker container image definition.

Build & Development Commands

All frontend/tauri commands run from the app/ directory:

cd app
npm ci                    # Install dependencies (required first time)
npx tauri dev             # Launch app in dev mode with hot reload (Vite on port 1420)
npx tauri build           # Production build (outputs to src-tauri/target/release/bundle/)
npm run build             # Frontend-only build (tsc + vite)
npm run test              # Run Vitest once
npm run test:watch        # Run Vitest in watch mode

Rust backend is compiled automatically by tauri dev/tauri build. To check Rust independently:

cd app/src-tauri
cargo check               # Type-check without full build
cargo build               # Build Rust backend only

Container image:

docker build -t triple-c-sandbox ./container

Linux Build Dependencies (Ubuntu/Debian)

sudo apt-get install -y libgtk-3-dev libwebkit2gtk-4.1-dev libayatana-appindicator3-dev librsvg2-dev libsoup-3.0-dev patchelf libssl-dev pkg-config build-essential

Architecture

Two-Process Model (Tauri IPC)

• React frontend (app/src/) renders UI in the OS webview
• Rust backend (app/src-tauri/src/) handles Docker API, credential storage, and terminal I/O
• Communication uses two patterns:
  • invoke() — request/response for discrete operations (CRUD, start/stop containers)
  • emit()/listen() — event streaming for continuous data (terminal I/O)

Terminal I/O Flow

User keystroke → xterm.js onData() → invoke("terminal_input") → mpsc channel → docker exec stdin
docker exec stdout → tokio task → emit("terminal-output-{sessionId}") → listen() → xterm.js write()

Frontend Structure (app/src/)

• store/appState.ts — Single Zustand store for all app state (projects, sessions, UI). The main area is a single ordered tab strip holding two tab kinds, keyed term:<id> and home:<id>; activeSessionId is derived from activeTabKey so exactly one thing is current. tabOrder is user-reorderable (drag, or Ctrl+Shift+←/→ via moveActiveTab) — so never treat a tab's position as identity: address tabs by key, and index only through tabOrder. moveTab deliberately does not activate what it moves.
  • The tab drag is pointer events, not HTML5 drag-and-drop, and must stay that way. Tauri's dragDropEnabled blocks HTML5 drag inside the webview on Windows, and it cannot simply be turned off: TerminalView needs Tauri's native drag-drop event because it is the only one that carries dropped file paths. An HTML5 drag also carries a DataTransfer, which the default handler types into any text field the drag is released over.
  • A new app-level shortcut must not swallow a text-editing chord. useKeyboardShortcuts binds on document in the capture phase, so inTextField() guards the arrow bindings — excluding xterm's helper textarea, which is an input-method shim rather than a field.
• hooks/ — All Tauri IPC calls are encapsulated in hooks (useTerminal, useProjects, useDocker, useSettings)
• lib/tauri-commands.ts — Typed invoke() wrappers; TypeScript types in lib/types.ts must match Rust models
• components/terminal/TerminalView.tsx — xterm.js integration with WebGL rendering, URL detection for OAuth flow
• components/layout/ — TopBar, MainTabs (the unified tab strip), Sidebar, StatusBar
• components/projects/ — ProjectRow (select-only list row), ProjectList, AddProjectDialog, and the editors reused by Project Home
• components/projects/home/ — Project Home, the main-area view for a project: Overview / Sessions / Automation / Config / Files. Per-project configuration lives here, not in modals — see "UI conventions" below.
• components/settings/ — Host-level settings: Docker, AWS, Web Terminal, STT, shared auth
• components/ui/ — Shared primitives. Use these; do not hand-roll replacements. Modal (the only correct way to build a dialog — it supplies role="dialog", aria-modal, focus trap and restore), Button, Toggle, Field, SegmentedControl, StatusIndicator, SaveIndicator, OverflowMenu, ToastHost, Tooltip

UI conventions

• Project config belongs in Project Home's Config tab, not a modal. Modals are reserved for short, genuinely modal tasks (add project, confirm removal, token acquisition). The app previously had ~12 hand-rolled modals; they were consolidated deliberately.
• Never bypass the design tokens. All colour comes from CSS custom properties in index.css. Filled buttons use --accent-emphasis (not --accent, which fails WCAG AA against white). Use --text-disabled rather than disabled:opacity-50.
• Never write focus:outline-none. A global :focus-visible ring is defined in index.css.
• Status must not be encoded in colour alone — StatusIndicator pairs a glyph with a word.
• Keyboard: Ctrl+T new terminal, Ctrl+Shift+W close tab, Ctrl+Tab cycle, Ctrl+1..9 jump, Ctrl+Shift+←/→ move the active tab. Ctrl+W is intentionally left alone — it is readline's kill-word inside the terminal, and plain Ctrl+←/→ is its word-wise cursor motion, which is why tab-moving takes Shift.

Backend Structure (app/src-tauri/src/)

• commands/ — Tauri command handlers. These are the IPC entry points called by invoke(). Beyond docker/project/settings/terminal: inspect_commands.rs (read-only views into a container — Claude sessions, installed capabilities, scheduler tasks), auth_bridge_commands.rs, auth_token_commands.rs.
• auth_bridge/ — Host-side loopback bridge so browser logins run inside a container can complete against the host browser. Discovers listeners by parsing /proc/net/tcp{,6} (the image has no ss/netstat/lsof), binds host 127.0.0.1 only, and tunnels in over the Docker API via socat. Opt-in per project.
• browser_view/ — Watch and take over the browser Claude drives with Playwright inside the container. Runs Playwright's own dashboard (browser.bind() + playwright-cli show) in the container and fronts it with a token-gated loopback proxy. Deliberately does not reuse the auth bridge's PortForward, which binds an unauthenticated port — fine for a throwaway OAuth listener, wrong for remote control of a browser. Host ports are confined to 47820..=47827 because CSP frame-src cannot express a port range and must enumerate them; a unit test asserts the Rust range matches tauri.conf.json. Opt-in per project.
  • popout.rs puts the same URL in a second OS window (WebviewUrl::External), so the view can be watched on another monitor or pinned on top while the main window is used for work. Three things it rests on: no capability lists that window, so it has no IPC surface — do not give it one; the app CSP does not apply, because it is a top-level document rather than a frame, and the token gate is what protects the port in both cases; and the window is owned by the session, so the supervisor's teardown closes it rather than leaving a window onto a viewer that no longer exists. It closes with destroy(), never close(), to stay clear of CloseRequested. The pane drops its iframe while popped out — two viewers can both drive the browser.
  • page.rs opens a page, which is the one thing the pane could not do. A URL plus a viewport: launch a browser in the container, browser.bind() it so the pane shows it, and keep the handle. Serves auth (the OAuth callback listener is in the container, so a container-side browser closes the loop with no host round trip and no auth bridge) and dev servers on container loopback. Verified: a second client cannot join a bound browser — chromium.connect() against the published endpoint times out in every URL form, because that socket speaks the dashboard's transport, not the public connect protocol. So whoever launches is the only process that can drive, which is why the helper is resident and why live resize applies to pages we opened and never to @playwright/mcp's (those take --viewport-size / PLAYWRIGHT_MCP_VIEWPORT_SIZE at launch). Control is a polled JSON file in /tmp — no port, no second listener — and a re-open with a helper already up navigates rather than relaunching, so a session signed in on one page survives to the next.
  • Resizing the window does not resize the page. The viewer is a CDP screencast: a bigger window is the same pixels drawn larger. page.setViewportSize() is what reflows (measured against a @media (max-width: 900px) rule), and match-window mode pushes the pop-out's settled Resized size into it — debounced by generation counter, since a drag emits continuously and each one costs a container exec.
  • lib.rs's on_window_event fires for every window and must stay guarded on label() == "main". Without that guard, closing a pop-out runs the app's shutdown: every container stopped, process exited.
  • Detection has to look past node_modules. claude mcp add … npx @playwright/mcp@latest installs into ~/.npm/_npx/<hash>/node_modules, not any node_modules, so detect.rs globs that cache as well as /workspace, $HOME/node_modules and npm root -g. It also hops from a wrapper playwright to its nested playwright-core: verified that npm does not hoist for global installs, and the wrapper ships no types/types.d.ts, so reading the wrapper alone reports a current build as "predates browser.bind()".
  • @playwright/mcp can never satisfy this pane. It bundles a playwright-core that binds, but never @playwright/cli, which is the viewer. Never offer it as a setup route — only as what binds sessions automatically once Playwright is present.
  • install.rs installs into /workspace, as claude, with --no-save. /workspace is not a bind mount — project directories are mounted at /workspace/{mount_name} — so this touches nothing of the user's, needs no sudo (npm's prefix is /usr, which is root-owned), and is on the module resolution path for scripts in the project. Browsers go to ~/.cache/ms-playwright as claude, i.e. the home volume.
  • Current base images ship Chromium's shared libraries; older ones do not — and a project keeps the base image it was first built from until it is migrated, so "older" is the normal case. Without them playwright install chromium downloads a browser that cannot launch, which is why installing Chrome via apt looks like a fix. install.rs asks install-deps --dry-run first and skips the apt step when the answer is "all present", saying so in the progress stream. Do not decide this by probing for library names: the dry-run simulates the same apt-get install the fix would run, so check and fix cannot disagree about what the dependency set is. Note that --dry-run exits 0 both when everything is installed and when Playwright has no list for the platform — match on its output, not its exit code. Either way the action ends by actually launching the browser to verify. @playwright/mcp wants the chrome channel specifically, so both browsers are offered.
• docker/ — Docker API layer using bollard:
  • client.rs — Singleton Docker connection via OnceLock
  • container.rs — Container lifecycle (create, start, stop, remove, inspect)
  • exec.rs — Attached exec streaming. create_attached_exec() is the single place an attached exec is opened; terminal sessions and the auth bridge both go through it.
  • image.rs — Image build/pull with progress streaming
  • gateway.rs — Optional LiteLLM sibling container giving Claude Code an Anthropic-format front end for providers that only speak OpenAI (see gateway-container/). Mirrors stt.rs. Its bind address is detected, never 0.0.0.0 — unlike STT, project containers consume it, so loopback alone is not always enough: Docker Desktop gets 127.0.0.1 (containers reach it via host.docker.internal), native Linux gets the default bridge gateway (172.17.0.1). GatewayBinding derives the bind address and the advertised base_url together so they cannot drift. A wildcard bind would be LAN-reachable — Docker's rules precede host firewalls — in front of a container config holding a billed provider key. It also always sets a LiteLLM master_key, since LiteLLM without one accepts any key.
  • migration.rs — Base-image migration: manifest capture via throwaway containers, the pure delta computation (dpkg-ownership filter, bind-mount exclusion, verbatim-copy set), and the crash-recovery state machine. See "Base-image migration" below.
  • legacy_cleanup.rs — One-release migration shim removing leftovers from the deleted MCP feature (containers labelled triple-c.mcp-server, triple-c-net-* networks). Deletable once users have migrated.
• web_terminal/ — Remote terminal access via axum HTTP+WebSocket server:
  • server.rs — Axum server lifecycle (start/stop), serves embedded HTML and handles WS upgrades
  • ws_handler.rs — Per-connection WebSocket handler with JSON protocol, session management, cleanup on disconnect
  • terminal.html — Self-contained xterm.js web UI embedded via include_str!()
• models/ — Serde structs (Project, Backend, BedrockConfig, OllamaConfig, LlamaCppConfig, OpenAiCompatibleConfig, ClaudeCodeSettings, ContainerInfo, AppSettings, WebTerminalSettings). These define the IPC contract with the frontend.
• storage/ — Persistence: projects_store.rs (JSON file with atomic writes), secure.rs (OS keychain via keyring crate), settings_store.rs

Container (container/)

• Dockerfile — Ubuntu 24.04 base with Claude Code, Node.js 22, Python 3.12, Rust, Docker CLI, git, gh, AWS CLI v2, ripgrep, pnpm, uv, ruff pre-installed, plus the shared libraries a browser links against (see below)
• Browser runtime libraries are baked in; browser binaries are not. A layer runs npx --yes playwright@latest install-deps chromium as root, so Playwright names its own dependencies and the list cannot rot against Ubuntu 24.04's t64 renames or a new Chromium dependency. Measured: +99 packages, +334 MiB unpacked / +119 MiB compressed, on both arches. Do not replace it with a hand-written apt list without pinning the Playwright version you derived it from — a chromium-only list saves ~94 MiB (Playwright's tools group: xvfb and the CJK fonts) and nothing more, because libgbm1 → mesa-libgallium → libllvm20 is ~213 MiB that no trimming removes.
  • The install-deps --dry-run call after it is a build-time assertion, not decoration: on a platform Playwright's table does not cover, install-deps prints a warning and returns having installed nothing with exit status 0. Without the assertion that ships a broken image behind a clean build log.
  • Baking the libraries but not the browsers is the whole point of the split. Browsers live in ~/.cache/ms-playwright (home volume) and already survive recreation and migration; a runtime apt-get install of the libraries lands in the writable layer, is re-paid after every Reset, and is lost on base-image migration, which replays apt from a manifest. The runtime approach converges on the worst state: a 400 MB browser present with its libraries gone.
  • The layer sits immediately after Node (npx is its only prerequisite) and well above the shim COPYs, so editing a shim does not re-run a multi-hundred-megabyte apt install.
• entrypoint.sh — UID/GID remapping to match host user, SSH key setup, git config, docker socket permissions, Claude Code settings.json injection, then sleep infinity
• triple-c-scheduler — Bash-based scheduled task system for recurring Claude Code invocations

/home/claude in the image is seed-only. It is the mount point of the named volume triple-c-home-{projectId}, so after a project's first start the image's copy of that directory is masked permanently and can never be updated again. A change you make under /home/claude in the Dockerfile or in entrypoint.sh's "copy this into the home dir" style reaches new projects only — existing ones will never see it, with or without a base-image migration.

So: anything that must stay upgradable belongs in /usr/local/bin or /opt, or must be seeded by entrypoint.sh at runtime (i.e. written on every start, from a source outside the home volume, the way CLAUDE_INSTRUCTIONS → ~/.claude/CLAUDE.md and the Mission Control skill copy already are). Putting it in the image's /home/claude and expecting an image update to deliver it is the mistake.

The flip side is the useful half of the same fact: Claude Code itself (~/.local/bin), cargo, uv, ruff, the OAuth login, ~/.claude.json, skills, transcripts, scheduler tasks and SSH keys all re-attach for free when a container is recreated from a different image — which is what makes base-image migration cheap.

Corporate CA certificates (docker/ca_certs.rs, entrypoint.sh)

A global AppSettings::ca_cert_path with a per-project Project::ca_cert_path override, accepting a single certificate file or a directory. Follows the SSH/AWS host-mount pattern: read-only bind mount at /tmp/.host-ca, applied by the entrypoint on every start, so it survives recreation, migration and Reset. Four things here are not obvious:

• update-ca-certificates globs *.crt, case-sensitively. A .pem that is merely copied into /usr/local/share/ca-certificates/ is ignored in total silence. Certificates are renamed — container_cert_name() in Rust, mirrored in a few lines of shell in entrypoint.sh (the Rust side carries the unit tests). A single-file mount lands at /tmp/.host-ca/<name>.crt so the entrypoint only ever sees a directory and the file keeps a recognisable name.
• The system store is not enough. Only curl/git/apt read it. Node — and therefore Claude Code itself — needs NODE_EXTRA_CA_CERTS; Python/requests need REQUESTS_CA_BUNDLE/SSL_CERT_FILE; Chrome/Chromium read neither and want their own NSS database at ~/.pki/nssdb, seeded with certutil (libnss3-tools, added to the image for this). The NSS step warns and continues if certutil is missing rather than failing the start.
• Those env vars are set from Rust at creation, never exported by the entrypoint. A terminal session is a docker exec, which inherits the container's configured env and sees nothing the entrypoint exported — the same lesson that made $BROWSER an image-level ENV. The bundle path is deterministic (/etc/ssl/certs/ca-certificates.crt), so Rust can set them up front. They are emitted empty when no CA is configured, for the MANAGED_AUTH_KEYS reason: docker commit bakes env into the snapshot image. Empty is safe — verified on Ubuntu 24.04 that curl, openssl s_client and Python's ssl behave exactly as with the vars unset.
• triple-c.ca-fingerprint covers the certificate bytes, not just the path. Replacing a rotated CA at the same location must recreate the container; the copy inside is made once, at start, so nothing else would notice. The entrypoint is stamped/idempotent on restart, and actively removes triple-c-*.crt when the setting is cleared — /usr/local/share rides the project's snapshot image, so turning the feature off has to undo, not merely stop.

Container Lifecycle

Containers use a stop/start model (not create/destroy). Installed packages persist across stops. The .claude config dir uses a named Docker volume (triple-c-claude-config-{projectId}), nested inside the home volume (triple-c-home-{projectId}), so OAuth tokens and Claude Code config survive container stop/start and container recreation.

Reset is the exception and it is destructive. rebuild_project_container calls remove_project_volumes, which deletes both volumes — so a Reset wipes ~/.claude, ~/.claude.json, the OAuth credential, installed skills, and session transcripts. That is intentional (Reset exists to get back to a clean base image), but do not describe Reset as preserving credentials.

Base-image migration (docker/migration.rs, commands/migration_commands.rs)

A container is created from triple-c-snapshot-{projectId}:latest whenever that image exists, and every recreation re-commits it — so without an explicit act, a project stays on the base image it was first built from forever and never picks up a new socat, a new /usr/local/bin shim or a security update. Migration is the non-destructive way out; Reset is the destructive one.

• Staleness is a surfaced signal, not an automatic trigger. triple-c.base-image-id records the lineage but is deliberately not compared in container_needs_recreation — see the long comment there. Comparing it would recreate every project from its own snapshot on the next base bump: churn on the old base, and it would consume the "you should migrate" signal without migrating. get_container_staleness surfaces it; migrate_project_to_base acts on it.
• A missing lineage label means "unknown, probe instead", never "stale".
• :latest keeps pointing at the old lineage until the final commit. That is what makes every crash before that point self-heal — start_project_container just recreates from the old snapshot. After the container swap, the new container's triple-c.migration-state=in-progress label plus the persisted state file let reconcile_project_statuses offer resume or rollback.
• Rollback restores the system layer only. The volumes are never touched at any point, so work done in $HOME during a migrated session survives a rollback. Say so in any UI copy.
• /var is never copied either, and that is the one way migration is more destructive than the ordinary recreate. A recreate builds from the project's snapshot, so /var/lib/postgresql rides along; a migration builds from the base and the apt replay hands back an empty cluster. Copying a live database's files onto a different base's version of the same package is a corruption risk, not a fix — so the answer is disclosure. unpreserved_data() reports first-level directories under /var/lib and /var/www that the base does not ship and that hold non-dpkg-owned files (which is what keeps /var/lib/apt and /var/lib/dpkg out of it), and the pre-flight, the banner and the finished report all name them. Do not make this silent.
• The rollback pin is not best-effort. After commit_container_snapshot the commit is the only copy of the old system layer, so a docker tag that fails — or succeeds without the reference resolving — aborts the migration before remove_container. Same rule in reverse for rollback_migration: the image is confirmed to exist before the container is destroyed.
• resume must check the container's triple-c.migration-state label, exactly as reconcile_migration does. Without it a record left behind by a failed commit "resumes" into the old, unmigrated container and commits it as migrated.
• Anything that stops, removes or recreates a project's container consults migration_commands::is_migrating. The window between remove_container and the create that follows looks exactly like "no container" to Start, and Reset would delete the volumes out from under a live run.
• /etc is never copied, only reported: the snapshot lineage has /etc/apt/sources.list.d/nodesource.sources where the current base has nodesource.list, and having both breaks every apt-get update on a duplicate source. Verified, not theoretical.
• docker diff is useless here — on a snapshot-derived container it reports only changes since the last commit. Migration diffs two filesystem manifests instead, filtered through dpkg ownership and presence-in-the-new-base. Measured on a real project, that turns 8,677 raw path differences into 2 genuinely user-authored ones.

Authentication

Per-project, independently configured:

• Anthropic (OAuth) — claude login in terminal, token persists in config volume
• AWS Bedrock — Static keys, profile, or bearer token injected as env vars
• Ollama — Connect to a local or remote Ollama server via ANTHROPIC_BASE_URL (e.g., http://host.docker.internal:11434)
• llama.cpp — Connect to a local or remote llama-server via ANTHROPIC_BASE_URL (e.g., http://host.docker.internal:8080, its default port)
• OpenAI Compatible — Connect through a gateway implementing the Anthropic Messages API (LiteLLM) via ANTHROPIC_BASE_URL + ANTHROPIC_AUTH_TOKEN

Claude Code only ever speaks the Anthropic Messages API (POST /v1/messages?beta=true) to ANTHROPIC_BASE_URL — never OpenAI's /v1/chat/completions. Ollama and llama.cpp implement /v1/messages natively, which is why each gets a plain base-URL backend with no translation shim. A server that only exposes an OpenAI-shaped API does not work behind any backend.

For every backend pointing at a custom endpoint (Backend::uses_custom_endpoint), all four ANTHROPIC_DEFAULT_{OPUS,SONNET,HAIKU,FABLE}_MODEL vars are pinned to the backend's configured model id, with an optional per-backend Haiku override. Without this, Claude Code's background calls resolve haiku to an Anthropic model id the local server does not have and fail silently. Anthropic and Bedrock deliberately keep Claude Code's own defaults. ANTHROPIC_SMALL_FAST_MODEL is deprecated and must not be used.

Styling

• Tailwind CSS v4 with the Vite plugin (@tailwindcss/vite). No separate tailwind config file.
• All colors use CSS custom properties in index.css :root (e.g., --bg-primary, --text-secondary, --accent)
• color-scheme: dark is set on :root for native dark-mode controls
• Do not add a global * { padding: 0 } reset — Tailwind v4 uses CSS @layer, and unlayered CSS overrides all layered utilities

Key Conventions

• Frontend types in lib/types.ts must stay in sync with Rust structs in models/
• Tauri commands are registered in lib.rs via .invoke_handler(tauri::generate_handler![...])
• capabilities/default.json grants permissions for plugin commands only (core:, dialog:, store:, opener:). Application commands registered through generate_handler! do not need an entry there — adding one is not required and none exists for any app command.
• The projects.json file uses atomic writes (write to .tmp, then rename()). Corrupted files are backed up to .bak.
• Adding project state that changes the container? container_needs_recreation() is entirely label-based — it does not diff the container's env. If a new setting affects the container's environment or configuration, you must also write a corresponding triple-c.* label at creation and compare it there, or the change will silently not take effect until some unrelated setting forces a rebuild. Never put a secret in a label; labels are readable via docker inspect. (triple-c.base-image-id is the one deliberate exception — it is written but not compared; the reasoning is in the comment beside the check.)
• Always write a triple-c.* label explicitly, even when the value is empty. Docker merges an image's labels into a container's at creation, and docker commit copies container labels onto the snapshot image — so a label stamped once rides that snapshot into every future container forever. Verified on this host, and it is not hypothetical: triple-c.mcp-fingerprint has not been written by any code since the MCP feature was removed, yet a snapshot image was found still carrying a non-empty one, which made its one-shot recreation shim recreate that project on every single start. Writing the key explicitly overrides the inherited value — the same defence MANAGED_AUTH_KEYS applies to env vars.
• New model fields need an explicit serde default when the correct default isn't the zero value. #[serde(default)] on a bool yields false; follow the default_full_permissions pattern in models/project.rs for anything that should default to true.
• Cross-platform paths: Docker socket is /var/run/docker.sock on Linux/macOS, //./pipe/docker_engine on Windows

Testing

Frontend tests use Vitest with jsdom environment and React Testing Library. Setup file at src/test/setup.ts. Run a single test file:

cd app
npx vitest run src/path/to/test.test.ts