Fix review findings: secrets in snapshots, URL spoofing, migration data loss

Adversarial review of the branch produced findings across four areas.
This addresses them, plus the Windows CI environment.

Secrets. commit_container_snapshot baked the container's full env into
the per-project snapshot image, so the shared OAuth token — and the AWS
keys, git token and gateway master key — outlived revocation and were
readable via docker inspect. Verified against Engine 29.6 that a commit
body's config merges over the container's: keys cannot be dropped but
can be overwritten, so all of them now commit as KEY=. clear_claude_token
additionally rewrites images from earlier builds and reports honestly
when a tag could not be rewritten.

The recommendation to move the token out of env entirely was not taken,
with reasoning: apiKeyHelper is a different auth method that outranks
CLAUDE_CODE_OAUTH_TOKEN rather than a transport for it, and no
file-based delivery exists. The durable exposure — the image — is what
is closed here. Separately noted, not fixed: entrypoint.sh captures the
token into the scheduler's .env inside the persisted volume.

URL spoofing. Three call sites reached openUrl with container-controlled
strings, one of which the review missed (the WebLinksAddon handler).
The sign-in URL was scraped from container output with a longest-match
tie-break and no userinfo check, so claude.ai@evil.tld rendered as
"claude.ai…" in a truncating element. There is now one sanitizer in
front of every sink — scheme allowlist, no userinfo, C0/C1 and quote
rejection, host allowlist for the sign-in case, first-match — and the
origin renders un-truncated. The toast is keyed so a changed URL
remounts, closing a bait-and-switch where the user read one URL and
clicked another.

Migration. The rollback pin was best-effort: a tag failure was logged
and the migration continued past remove_container, after which the
final commit overwrote the only copy of the old system layer. It now
aborts before anything destructive and reads the tag back. /var was
destroyed while the ordinary recreate path preserves it — making the
"safe" alternative to Reset more destructive than Reset's alternative;
data-bearing subtrees are now detected and disclosed in the pre-flight
rather than copied, since tarring a live database onto a different
base's packages is a corruption risk. resume_migration now verifies the
migration-state label instead of reporting success for a container that
never swapped. dismiss actually resolves the record rather than leaving
the feature permanently refusing to migrate. Start and Reset are guarded
while a migration is live.

Lifecycle. The gateway no longer publishes on 0.0.0.0 — bind address and
advertised URL are derived together so they cannot drift. Disabling it
now stops it. App exit runs teardown concurrently under a budget with a
visible shutting-down state instead of blocking for minutes. Auto-starts
retry when Docker is not up yet, and the polling-recovery path now
reconciles, so interrupted migrations are still recovered. Auth-bridge
forwards are capped, closing a container-driven fd exhaustion.

Windows CI. build-windows failed on this branch with "linker link.exe
not found". The runner had no MSVC build tools and the workflow assumed
a hand-provisioned machine, so a bare runner registers, accepts jobs and
fails at link time after downloading the whole crate graph. The job now
installs the VC++ workload when vswhere cannot find it, matching how it
already conditionally installs Rust and Node.

192 Rust tests, 274 frontend tests, both builds clean, zero warnings.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

app/src/hooks/useClaudeAuth.test.ts

@@ -35,6 +35,50 @@ describe("extractSignInUrl", () => {
     const text = `https://claude.ai/oauth/authorize?code=tr\n${full}\n`;
     expect(extractSignInUrl(text)).toBe(full);
   });
+
+  // ── The spoof this function exists to refuse ──────────────────────────────
+  // The transcript is container output. Everything below is a URL a misbehaving
+  // sandboxed agent can print at will, and the modal renders whatever comes
+  // back under a heading that says "Sign in with Anthropic".
+
+  it("rejects userinfo that makes an attacker's host read as Anthropic's", () => {
+    // Displays as `https://claude.ai...` in anything that truncates; navigates
+    // to evil.tld and harvests the real credential.
+    const spoof =
+      "https://claude.ai@evil.tld/oauth/authorize?" + "padding=".repeat(40);
+    expect(extractSignInUrl(`Use this url to sign in:\n${spoof}\n`)).toBeNull();
+  });
+
+  it("does not let a longer hostile URL displace the real one", () => {
+    const real = "https://claude.ai/oauth/authorize?code=true&client_id=abc";
+    const longer =
+      "https://evil.tld/oauth/authorize?" + "x".repeat(real.length * 2);
+    expect(extractSignInUrl(`${real}\n${longer}\n`)).toBe(real);
+    // ...and the same when the hostile one is printed first.
+    expect(extractSignInUrl(`${longer}\n${real}\n`)).toBe(real);
+  });
+
+  it("rejects a host that merely contains an Anthropic domain", () => {
+    expect(
+      extractSignInUrl("Sign in: https://claude.ai.evil.tld/oauth/authorize\n"),
+    ).toBeNull();
+    expect(
+      extractSignInUrl("Sign in: https://evil.tld/claude.ai/oauth/authorize\n"),
+    ).toBeNull();
+  });
+
+  it("rejects non-http schemes and control characters smuggled into the link", () => {
+    expect(extractSignInUrl("Open javascript:alert(1) to continue\n")).toBeNull();
+    expect(
+      extractSignInUrl("https://claude.ai/oauth\u0000/authorize\n"),
+    ).toBe("https://claude.ai/oauth");
+  });
+
+  it("takes the first legitimate link, not the longest", () => {
+    const first = "https://claude.ai/oauth/authorize?code=true";
+    const second = "https://platform.claude.com/oauth/authorize?code=true&more=1";
+    expect(extractSignInUrl(`${first}\n${second}\n`)).toBe(first);
+  });
 });
 
 describe("authErrorMessage", () => {