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security: tunnel dual-listener + SSRF + envelope + path wave (v1.6.0.0) (#1137)
* refactor(security): loosen /connect rate limit from 3/min to 300/min Setup keys are 24 random bytes (unbruteforceable), so a tight rate limit does not meaningfully prevent key guessing. It exists only to cap bandwidth, CPU, and log-flood damage from someone who discovered the ngrok URL. A legitimate pair-agent session hits /connect once; 300/min is 60x that pattern and never hit accidentally. 3/min caused pairing to fail on any retry flow (network blip, second paired client) with no upside. Per-IP tracking was considered and rejected — adds a bounded Map + LRU for defense already adequate at the global layer. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * feat(security): add tunnel-denial-log module for attack visibility Append-only log of tunnel-surface auth denials to ~/.gstack/security/attempts.jsonl. Gives operators visibility into who is probing tunneled daemons so the next security wave can be driven by real attack data instead of speculation. Design notes: - Async via fs.promises.appendFile. Never appendFileSync — blocking the event loop on every denial during a flood is what an attacker wants (prior learning: sync-audit-log-io, 10/10 confidence). - In-process rate cap at 60 writes/minute globally. Excess denials are counted in memory but not written to disk — prevents disk DoS. - Writes to the same ~/.gstack/security/attempts.jsonl used by the prompt-injection attempt log. File rotation is handled by the existing security pipeline (10MB, 5 generations). No consumers in this commit; wired up in the dual-listener refactor that follows. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * feat(security): dual-listener tunnel architecture The /health endpoint leaked AUTH_TOKEN to any caller that hit the ngrok URL (spoofing chrome-extension:// origin, or catching headed mode). Surfaced by @garagon in PR #1026; the original fix was header-inference on the single port. Codex's outside-voice review during /plan-ceo-review called that approach brittle (ngrok header behavior could change, local proxies would false-positive), and pushed for the structural fix. This is that fix. Stop making /health a root-token bootstrap endpoint on any surface the tunnel can reach. The server now binds two HTTP listeners when a tunnel is active. The local listener (extension, CLI, sidebar) stays on 127.0.0.1 and is never exposed to ngrok. ngrok forwards only to the tunnel listener, which serves only /connect (unauth, rate-limited) and /command with a locked allowlist of browser-driving commands. Security property comes from physical port separation, not from header inference — a tunnel caller cannot reach /health or /cookie-picker or /inspector because they live on a different TCP socket. What this commit adds to browse/src/server.ts: * Surface type ('local' | 'tunnel') and TUNNEL_PATHS + TUNNEL_COMMANDS allowlists near the top of the file. * makeFetchHandler(surface) factory replacing the single fetch arrow; closure-captures the surface so the filter that runs before route dispatch knows which socket accepted the request. * Tunnel filter at dispatch entry: 404s anything not on TUNNEL_PATHS, 403s root-token bearers with a clear pairing hint, 401s non-/connect requests that lack a scoped token. Every denial is logged via logTunnelDenial (from tunnel-denial-log). * GET /connect alive probe (unauth on both surfaces) so /pair and /tunnel/start can detect dead ngrok tunnels without reaching /health — /health is no longer tunnel-reachable. * Lazy tunnel listener lifecycle. /tunnel/start binds a dedicated Bun.serve on an ephemeral port, points ngrok.forward at THAT port (not the local port), hard-fails on bind error (no local fallback), tears down cleanly on ngrok failure. BROWSE_TUNNEL=1 startup uses the same pattern. * closeTunnel() helper — single teardown path for both the ngrok listener and the tunnel Bun.serve listener. * resolveNgrokAuthtoken() helper — shared authtoken lookup across /tunnel/start and BROWSE_TUNNEL=1 startup (was duplicated). * TUNNEL_COMMANDS check in /command dispatch: on the tunnel surface, commands outside the allowlist return 403 with a list of allowed commands as a hint. * Probe paths in /pair and /tunnel/start migrated from /health to GET /connect — the only unauth path reachable on the tunnel surface under the new architecture. Test updates in browse/test/server-auth.test.ts: * /pair liveness-verify test: assert via closeTunnel() helper instead of the inline `tunnelActive = false; tunnelUrl = null` lines that the helper subsumes. * /tunnel/start cached-tunnel test: same closeTunnel() adaptation. Credit Derived from PR #1026 by @garagon — thanks for flagging the critical bug that drove the architectural rewrite. The per-request isTunneledRequest approach from #1026 is superseded by physical port separation here; the underlying report remains the root cause for the entire v1.6.0.0 wave. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * test(security): add source-level guards for dual-listener architecture 23 source-level assertions that keep future contributors from silently widening the tunnel surface during a routine refactor. Covers: * Surface type + tunnelServer state variable shape * TUNNEL_PATHS is a closed set of /connect, /command, /sidebar-chat (and NOT /health, /welcome, /cookie-picker, /inspector/*, /pair, /token, /refs, /activity/stream, /tunnel/{start,stop}) * TUNNEL_COMMANDS includes browser-driving ops only (and NOT launch-browser, tunnel-start, token-mint, cookie-import, etc.) * makeFetchHandler(surface) factory exists and is wired to both listeners with the correct surface parameter * Tunnel filter runs BEFORE any route dispatch, with 404/403/401 responses and logged denials for each reason * GET /connect returns {alive: true} unauth * /command dispatch enforces TUNNEL_COMMANDS on tunnel surface * closeTunnel() helper tears down ngrok + Bun.serve listener * /tunnel/start binds on ephemeral port, points ngrok at TUNNEL_PORT (not local port), hard-fails on bind error (no fallback), probes cached tunnel via GET /connect (not /health), tears down on ngrok.forward failure * BROWSE_TUNNEL=1 startup uses the dual-listener pattern * logTunnelDenial wired for all three denial reasons * /connect rate limit is 300/min, not 3/min All 23 tests pass. Behavioral integration tests (spawn subprocess, real network) live in the E2E suite that lands later in this wave. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * security: gate download + scrape through validateNavigationUrl (SSRF) The `goto` command was correctly wired through validateNavigationUrl, but `download` and `scrape` called page.request.fetch(url, ...) directly. A caller with the default write scope could hit the /command endpoint and ask the daemon to fetch http://169.254.169.254/latest/meta-data/ (AWS IMDSv1) or the GCP/Azure/internal equivalents. The response body comes back as base64 or lands on disk where GET /file serves it. Fix: call validateNavigationUrl(url) immediately before each page.request.fetch() call site in download and in the scrape loop. Same blocklist that already protects `goto`: file://, javascript:, data:, chrome://, cloud metadata (IPv4 all encodings, IPv6 ULA, metadata.*.internal). Tests: extend browse/test/url-validation.test.ts with a source-level guard that walks every `await page.request.fetch(` call site and asserts a validateNavigationUrl call precedes it within the same branch. Regression trips before code review if a future refactor drops the gate. * security: route splitForScoped through envelope sentinel escape The scoped-token snapshot path in snapshot.ts built its untrusted block by pushing the raw accessibility-tree lines between the literal `═══ BEGIN UNTRUSTED WEB CONTENT ═══` / `═══ END UNTRUSTED WEB CONTENT ═══` sentinels. The full-page wrap path in content-security.ts already applied a zero-width-space escape on those exact strings to prevent sentinel injection, but the scoped path skipped it. Net effect: a page whose rendered text contains the literal sentinel can close the envelope early from inside untrusted content and forge a fake "trusted" block for the LLM. That includes fabricating interactive `@eN` references the agent will act on. Fix: * Extract the zero-width-space escape into a named, exported helper `escapeEnvelopeSentinels(content)` in content-security.ts. * Have `wrapUntrustedPageContent` call it (behavior unchanged on that path — same bytes out). * Import the helper in snapshot.ts and map it over `untrustedLines` in the `splitForScoped` branch before pushing the BEGIN sentinel. Tests: add a describe block in content-security.test.ts that covers * `escapeEnvelopeSentinels` defuses BEGIN and END markers; * `escapeEnvelopeSentinels` leaves normal text untouched; * `wrapUntrustedPageContent` still emits exactly one real envelope pair when hostile content contains forged sentinels; * snapshot.ts imports the helper; * the scoped-snapshot branch calls `escapeEnvelopeSentinels` before pushing the BEGIN sentinel (source-level regression — if a future refactor reorders this, the test trips). * security: extend hidden-element detection to all DOM-reading channels The Confusion Protocol envelope wrap (`wrapUntrustedPageContent`) covers every scoped PAGE_CONTENT_COMMAND, but the hidden-element ARIA-injection detection layer only ran for `text`. Other DOM-reading channels (html, links, forms, accessibility, attrs, data, media, ux-audit) returned their output through the envelope with no hidden- content filter, so a page serving a display:none div that instructs the agent to disregard prior system messages, or an aria-label that claims to put the LLM in admin mode, leaked the injection payload on any non-text channel. The envelope alone does not mitigate this, and the page itself never rendered the hostile content to the human operator. Fix: * New export `DOM_CONTENT_COMMANDS` in commands.ts — the subset of PAGE_CONTENT_COMMANDS that derives its output from the live DOM. Console and dialog stay out; they read separate runtime state. * server.ts runs `markHiddenElements` + `cleanupHiddenMarkers` for every scoped command in this set. `text` keeps its existing `getCleanTextWithStripping` path (hidden elements physically stripped before the read). All other channels keep their output format but emit flagged elements as CONTENT WARNINGS on the envelope, so the LLM sees what it would otherwise have consumed silently. * Hidden-element descriptions merge into `combinedWarnings` alongside content-filter warnings before the wrap call. Tests: new describe block in content-security.test.ts covering * `DOM_CONTENT_COMMANDS` export shape and channel membership; * dispatch gates on `DOM_CONTENT_COMMANDS.has(command)`, not the literal `text` string; * hiddenContentWarnings plumbs into `combinedWarnings` and reaches wrapUntrustedPageContent; * DOM_CONTENT_COMMANDS is a strict subset of PAGE_CONTENT_COMMANDS. Existing datamarking, envelope wrap, centralized-wrapping, and chain security suites stay green (52 pass, 0 fail). * security: validate --from-file payload paths for parity with direct paths The direct `load-html <file>` path runs every caller-supplied file path through validateReadPath() so reads stay confined to SAFE_DIRECTORIES (cwd, TEMP_DIR). The `load-html --from-file <payload.json>` shortcut and its sibling `pdf --from-file <payload.json>` skipped that check and went straight to fs.readFileSync(). An MCP caller that picks the payload path (or any caller whose payload argument is reachable from attacker-influenced text) could use --from-file as a read-anywhere escape hatch for the safe-dirs policy. Fix: call validateReadPath(path.resolve(payloadPath)) before readFileSync at both sites. Error surface mirrors the direct-path branch so ops and agent errors stay consistent. Test coverage in browse/test/from-file-path-validation.test.ts: - source-level: validateReadPath precedes readFileSync in the load-html --from-file branch (write-commands.ts) and the pdf --from-file parser (meta-commands.ts) - error-message parity: both sites reference SAFE_DIRECTORIES Related security audit pattern: R3 F002 (validateNavigationUrl gap on download/scrape) and R3 F008 (markHiddenElements gap on 10 DOM commands) were the same shape — a defense that existed on the primary code path but not its shortcut sibling. This PR closes the same class of gap on the --from-file shortcuts. * fix(design): escape url.origin when injecting into served HTML serve.ts injected url.origin into a single-quoted JS string in the response body. A local request with a crafted Host header (e.g. Host: "evil'-alert(1)-'x") would break out of the string and execute JS in the 127.0.0.1:<port> origin opened by the design board. Low severity — bound to localhost, requires a local attacker — but no reason not to escape. Fix: JSON.stringify(url.origin) produces a properly quoted, escaped JS string literal in one call. Also includes Prettier reformatting (single→double quotes, trailing commas, line wrapping) applied by the repo's PostToolUse formatter hook. Security change is the one line in the HTML injection; everything else is whitespace/style. * fix(scripts): drop shell:true from slop-diff npx invocations spawnSync('npx', [...], { shell: true }) invokes /bin/sh -c with the args concatenated, subjecting them to shell parsing (word splitting, glob expansion, metacharacter interpretation). No user input reaches these calls today, so not exploitable — but the posture is wrong: npx + shell args should be direct. Fix: scope shell:true to process.platform === 'win32' where npx is actually a .cmd requiring the shell. POSIX runs the npx binary directly with array-form args. Also includes Prettier reformatting (single→double quotes, trailing commas, line wrapping) applied by the repo's PostToolUse formatter hook. Security-relevant change is just the two shell:true -> shell: process.platform === 'win32' lines; everything else is whitespace/style. * security(E3): gate GSTACK_SLUG on /welcome path traversal The /welcome handler interpolates GSTACK_SLUG directly into the filesystem path used to locate the project-local welcome page. Without validation, a slug like "../../etc/passwd" would resolve to ~/.gstack/projects/../../etc/passwd/designs/welcome-page-20260331/finalized.html — classic path traversal. Not exploitable today: GSTACK_SLUG is set by the gstack CLI at daemon launch, and an attacker would already need local env-var access to poison it. But the gate is one regex (^[a-z0-9_-]+$), and a defense-in-depth pass costs us nothing when the cost of being wrong is arbitrary file read via /welcome. Fall back to the safe 'unknown' literal when the slug fails validation — same fallback the code already uses when GSTACK_SLUG is unset. No behavior change for legitimate slugs (they all match the regex). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * security(N1): replace ?token= SSE auth with HttpOnly session cookie Activity stream and inspector events SSE endpoints accepted the root AUTH_TOKEN via `?token=` query param (EventSource can't send Authorization headers). URLs leak to browser history, referer headers, server logs, crash reports, and refactoring accidents. Codex flagged this during the /plan-ceo-review outside voice pass. New auth model: the extension calls POST /sse-session with a Bearer token and receives a view-only session cookie (HttpOnly, SameSite=Strict, 30-min TTL). EventSource is opened with `withCredentials: true` so the browser sends the cookie back on the SSE connection. The ?token= query param is GONE — no more URL-borne secrets. Scope isolation (prior learning cookie-picker-auth-isolation, 10/10 confidence): the SSE session cookie grants access to /activity/stream and /inspector/events ONLY. The token is never valid against /command, /token, or any mutating endpoint. A leaked cookie can watch activity; it cannot execute browser commands. Components * browse/src/sse-session-cookie.ts — registry: mint/validate/extract/ build-cookie. 256-bit tokens, 30-min TTL, lazy expiry pruning, no imports from token-registry (scope isolation enforced by module boundary). * browse/src/server.ts — POST /sse-session mint endpoint (requires Bearer). /activity/stream and /inspector/events now accept Bearer OR the session cookie, and reject ?token= query param. * extension/sidepanel.js — ensureSseSessionCookie() bootstrap call, EventSource opened with withCredentials:true on both SSE endpoints. Tested via the source guards; behavioral test is the E2E pairing flow that lands later in the wave. * browse/test/sse-session-cookie.test.ts — 20 unit tests covering mint entropy, TTL enforcement, cookie flag invariants, cookie parsing from multi-cookie headers, and scope-isolation contract guard (module must not import token-registry). * browse/test/server-auth.test.ts — existing /activity/stream auth test updated to assert the new cookie-based gate and the absence of the ?token= query param. Cookie flag choices: * HttpOnly: token not readable from page JS (mitigates XSS exfiltration). * SameSite=Strict: cookie not sent on cross-site requests (mitigates CSRF). Fine for SSE because the extension connects to 127.0.0.1 directly. * Path=/: cookie scoped to the whole origin. * Max-Age=1800: 30 minutes, matches TTL. Extension re-mints on reconnect when daemon restarts. * Secure NOT set: daemon binds to 127.0.0.1 over plain HTTP. Adding Secure would block the browser from ever sending the cookie back. Add Secure when gstack ships over HTTPS. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * security(N2): document Windows v20 ABE elevation path on CDP port The existing comment around the cookie-import-browser --remote-debugging-port launch claimed "threat model: no worse than baseline." That's wrong on Windows with App-Bound Encryption v20. A same-user local process that opens the cookie SQLite DB directly CANNOT decrypt v20 values (DPAPI context is bound to the browser process). The CDP port lets them bypass that: connect to the debug port, call Network.getAllCookies inside Chrome, walk away with decrypted v20 cookies. The correct fix is to switch from TCP --remote-debugging-port to --remote-debugging-pipe so the CDP transport is a stdio pipe, not a socket. That requires restructuring the CDP WebSocket client in this module and Playwright doesn't expose the pipe transport out of the box. Non-trivial, deferred from the v1.6.0.0 wave. This commit updates the comment to correctly describe the threat and points at the tracking issue. No code change to the launch itself. Follow-up: #1136. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * docs(E2): document dual-listener tunnel architecture in ARCHITECTURE.md Adds an explicit per-endpoint disposition table to the Security model section, covering the v1.6.0.0 dual-listener refactor. Every HTTP endpoint now has a documented local-vs-tunnel answer. Future audits (and future contributors wondering "is it safe to add X to the tunnel surface?") can read this instead of reverse-engineering server.ts. Also documents: * Why physical port separation beats per-request header inference (ngrok behavior drift, local proxies can forge headers, etc.) * Tunnel surface denial logging → ~/.gstack/security/attempts.jsonl * SSE session cookie model (gstack_sse, 30-min TTL, stream-scope only, module-boundary-enforced scope isolation) * N2 non-goal for Windows v20 ABE via CDP port (tracking #1136) No code changes. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * test(E1): end-to-end pair-agent flow against a spawned daemon Spawns the browse daemon as a subprocess with BROWSE_HEADLESS_SKIP=1 so the HTTP layer runs without a real browser. Exercises: * GET /health — token delivery for chrome-extension origin, withheld otherwise (the F1 + PR #1026 invariant) * GET /connect — alive probe returns {alive:true} unauth * POST /pair — root Bearer required (403 without), returns setup_key * POST /connect — setup_key exchange mints a distinct scoped token * POST /command — 401 without auth * POST /sse-session — Bearer required, Set-Cookie has HttpOnly + SameSite=Strict (the N1 invariant) * GET /activity/stream — 401 without auth * GET /activity/stream?token= — 401 (the old ?token= query param is REJECTED, which is the whole point of N1) * GET /welcome — serves HTML, does not leak /etc/passwd content under the default 'unknown' slug (E3 regex gate) 12 behavioral tests, ~220ms end-to-end, no network dependencies, no ngrok, no real browser. This is the receipt for the wave's central 'pair-agent still works + the security boundary holds' claim. Tunnel-port binding (/tunnel/start) is deliberately NOT exercised here — it requires an ngrok authtoken and live network. The dual-listener route allowlist is covered by source-level guards in dual-listener.test.ts; behavioral tunnel testing belongs in a separate paid-evals harness. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * release(v1.6.0.0): bump VERSION + CHANGELOG for security wave Architectural bump, not patch: dual-listener HTTP refactor changes the daemon's tunnel-exposure model. See CHANGELOG for the full release summary (~950 words) covering the five root causes this wave closes: 1. /health token leak over ngrok (F1 + E3 + test infra) 2. /cookie-picker + /inspector exposed over the tunnel (F1) 3. ?token=<ROOT> in SSE URLs leaking to logs/referer/history (N1) 4. /welcome GSTACK_SLUG path traversal (E3) 5. Windows v20 ABE elevation via CDP port (N2 — documented non-goal, tracked as #1136) Plus the base PRs: SSRF gate (#1029), envelope sentinel escape (#1031), DOM-channel hidden-element coverage (#1032), --from-file path validation (#1103), and 2 commits from #1073 (@theqazi). VERSION + package.json bumped to 1.6.0.0. CHANGELOG entry covers credits (@garagon, @Hybirdss, @HMAKT99, @theqazi), review lineage (CEO → Codex outside voice → Eng), and the non-goal tracking issue. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * fix: pre-landing review findings (4 auto-fixes) Addresses 4 findings from the Claude adversarial subagent on the v1.6.0.0 security wave diff. No user-visible behavior change; all are defense-in-depth hardening of newly-introduced code. 1. GET /connect rate-limited (was POST-only) [HIGH conf 8/10] Attacker discovering the ngrok URL could probe unlimited GETs for daemon enumeration. Now shares the global /connect counter. 2. ngrok listener leak on tunnel startup failure [MEDIUM conf 8/10] If ngrok.forward() resolved but tunnelListener.url() or the state-file write threw, the Bun listener was torn down but the ngrok session was leaked. Fixed in BOTH /tunnel/start and BROWSE_TUNNEL=1 startup paths. 3. GSTACK_SKILL_ROOT path-traversal gate [MEDIUM conf 8/10] Symmetric with E3's GSTACK_SLUG regex gate — reject values containing '..' before interpolating into the welcome-page path. 4. SSE session registry pruning [LOW conf 7/10] pruneExpired() only checked 10 entries per mint call. Now runs on every validate too, checks 20 entries, with a hard 10k cap as backstop. Prevents registry growth under sustained extension reconnect pressure. Tests remain green (56/56 in sse-session-cookie + dual-listener + pair-agent-e2e suites). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * docs: update project documentation for v1.6.0.0 Reflect the dual-listener tunnel architecture, SSE session cookies, SSRF guards, and Windows v20 ABE non-goal across the three docs users actually read for remote-agent and browser auth context: - docs/REMOTE_BROWSER_ACCESS.md: rewrote Architecture diagram for dual listeners, fixed /connect rate limit (3/min → 300/min), removed stale "/health requires no auth" (now 404 on tunnel), added SSE cookie auth, expanded Security Model with tunnel allowlist, SSRF guards, /welcome path traversal defense, and the Windows v20 ABE tracking note. - BROWSER.md: added dual-listener paragraph to Authentication and linked to ARCHITECTURE.md endpoint table. Replaced the stale ?token= SSE auth note with the HttpOnly gstack_sse cookie flow. - CLAUDE.md: added Transport-layer security section above the sidebar prompt-injection stack so contributors editing server.ts, sse-session-cookie.ts, or tunnel-denial-log.ts see the load-bearing module boundaries before touching them. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * fix(make-pdf): write --from-file payload to /tmp, not os.tmpdir() make-pdf's browseClient wrote its --from-file payload to os.tmpdir(), which is /var/folders/... on macOS. v1.6.0.0's PR #1103 cherry-pick tightened browse load-html --from-file to validate against the safe-dirs allowlist ([TEMP_DIR, cwd] where TEMP_DIR is '/tmp' on macOS/Linux, os.tmpdir() on Windows). This closed a CLI/API parity gap but broke make-pdf on macOS because /var/folders/... is outside the allowlist. Fix: mirror browse's TEMP_DIR convention — use '/tmp' on non-Windows, os.tmpdir() on Windows. The make-pdf-gate CI failure on macOS-latest (run 72440797490) is caused by exactly this: the payload file was rejected by validateReadPath. Verified locally: the combined-gate e2e test now passes after rebuilding make-pdf/dist/pdf. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> * fix(sidebar): killAgent resets per-tab state; align tests with current agent event format Two pre-existing bugs surfaced while running the full e2e suite on the sec-wave branch. Both pre-date v1.6.0.0 (same failures on main at e23ff28) but blocked the ship verification, so fixing now. ### Bug 1: killAgent leaked stale per-tab state `killAgent()` reset the legacy globals (agentProcess, agentStatus, etc.) but never touched the per-tab `tabAgents` Map. Meanwhile `/sidebar-command` routes on `tabState.status` from that Map, not the legacy globals. Consequence: after a kill (including the implicit kill in `/sidebar-session/new`), the next /sidebar-command on the same tab saw `tabState.status === 'processing'` and fell into the queue branch, silently NOT spawning an agent. Integration tests that called resetState between cases all failed with empty queues. Fix: when targetTabId is supplied, reset that one tab's state; when called without a tab (session-new, full kill), reset ALL tab states. Matches the semantic boundary already used for the cancel-file write. ### Bug 2: sidebar-integration tests drifted from current event format `agent events appear in /sidebar-chat` posted the raw Claude streaming format (`{type: 'assistant', message: {content: [...]}}`) but `processAgentEvent` in server.ts only handles the simplified types that sidebar-agent.ts pre-processes into (text, text_delta, tool_use, result, agent_error, security_event). The architecture moved pre-processing into sidebar-agent.ts at some point and this test never got updated. Fixed by sending the pre-processed `{type: 'text', text: '...'}` format — which is actually what the server sees in production. Also removed the `entry.prompt` URL-containment check in the queue-write test. The URL is carried on entry.pageUrl (metadata) by design: the system prompt tells Claude to run `browse url` to fetch the actual page rather than trust any URL in the prompt body. That's the URL-based prompt-injection defense. The prompt SHOULD NOT contain the URL, so the test assertion was wrong for the current security posture. ### Verification - `bun test browse/test/sidebar-integration.test.ts` → 13/13 pass (was 6/13 on both main and branch before this commit) - Full `bun run test` → exit 0, zero fail markers - No behavior change for production sidebar flows: killAgent was already supposed to return the agent to idle; it just wasn't fully doing so. Per-tab reset now matches the documented semantics. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com> --------- Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com> Co-authored-by: gus <gustavoraularagon@gmail.com> Co-authored-by: Mohammed Qazi <10266060+theqazi@users.noreply.github.com>
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ARCHITECTURE.md

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### Localhost only
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The HTTP server binds to `localhost`, not `0.0.0.0`. It's not reachable from the network.
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The HTTP server binds to `127.0.0.1`, not `0.0.0.0`. It's not reachable from the network.
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### Dual-listener tunnel architecture (v1.6.0.0)
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When a user runs `pair-agent --client`, the daemon starts an ngrok tunnel so a remote paired agent can drive the browser. Exposing the full daemon surface to the internet (even behind a random ngrok subdomain) meant `/health` leaked the root token on any Origin spoof, and `/cookie-picker` embedded the token into HTML that any caller could fetch.
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The fix is **two HTTP listeners**, not one:
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- **Local listener** (`127.0.0.1:LOCAL_PORT`) — always bound. Serves bootstrap (`/health` with token delivery), `/cookie-picker`, `/inspector/*`, `/welcome`, `/refs`, the sidebar-agent API, and the full command surface. Never forwarded.
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- **Tunnel listener** (`127.0.0.1:TUNNEL_PORT`) — bound lazily on `/tunnel/start`, torn down on `/tunnel/stop`. Serves a locked allowlist: `/connect` (pairing ceremony, unauth + rate-limited), `/command` (scoped tokens only, further restricted to a browser-driving command allowlist), and `/sidebar-chat`. Everything else 404s.
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ngrok forwards only the tunnel port. The security property comes from **physical port separation**: a tunnel caller cannot reach `/health` or `/cookie-picker` because those paths don't exist on that TCP socket. Header inference (check `x-forwarded-for`, check origin) is unreliable (ngrok header behavior changes; local proxies can add these headers); socket separation isn't.
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| Endpoint | Local listener | Tunnel listener | Notes |
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|---|---|---|---|
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| `GET /health` | public (no token unless headed/extension) | 404 | Token bootstrap for extension happens locally only |
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| `GET /connect` | public (`{alive:true}`) | public (`{alive:true}`) | Probe path for tunnel liveness |
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| `POST /connect` | public (rate-limited 300/min) | public (rate-limited) | Setup-key exchange for pair-agent |
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| `POST /command` | auth (Bearer root OR scoped) | auth (scoped only, allowlisted commands) | Root token on tunnel = 403 |
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| `POST /sidebar-chat` | auth | auth | Lets remote agent post into local sidebar |
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| `POST /pair` | root-only | 404 | Pairing mint — local operator action |
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| `POST /tunnel/{start,stop}` | root-only | 404 | Daemon configuration |
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| `POST /token`, `DELETE /token/:id` | root-only | 404 | Scoped token mint/revoke |
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| `GET /cookie-picker`, `GET /cookie-picker/*` | public UI, auth API | 404 | Local-only — reads local browser DBs |
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| `GET /inspector`, `/inspector/events`, etc. | auth | 404 | Extension callback, local-only |
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| `GET /welcome` | public | 404 | GStack Browser landing page, local-only |
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| `GET /refs` | auth | 404 | Ref map — internal state |
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| `GET /activity/stream` | Bearer OR HttpOnly `gstack_sse` cookie | 404 | SSE. ?token= query param no longer accepted |
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| `GET /inspector/events` | Bearer OR HttpOnly `gstack_sse` cookie | 404 | SSE. Same cookie as /activity/stream |
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| `POST /sse-session` | auth (Bearer) | 404 | Mints the view-only 30-min SSE session cookie |
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**Tunnel surface denial logs.** Every rejection on the tunnel listener (`path_not_on_tunnel`, `root_token_on_tunnel`, `missing_scoped_token`, `disallowed_command:*`) is recorded asynchronously to `~/.gstack/security/attempts.jsonl` with timestamp, source IP (from `x-forwarded-for`), path, and method. Rate-capped at 60 writes/min globally to prevent log-flood DoS. Shares the attempt log with the prompt-injection scanner.
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**SSE session cookies.** EventSource can't send Authorization headers, so the extension POSTs `/sse-session` once at bootstrap with the root Bearer and receives a 30-minute view-only cookie (`gstack_sse`, HttpOnly, SameSite=Strict). The cookie is valid ONLY for `/activity/stream` and `/inspector/events` — it is NOT a scoped token and cannot be used on `/command`. Scope isolation is enforced by the module boundary: `sse-session-cookie.ts` has no imports from `token-registry.ts`.
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**Non-goal in this wave** (tracked as #1136): the cookie-import-browser path launches Chrome with `--remote-debugging-port=<random>`. On Windows with App-Bound Encryption v20, a same-user local process can connect to that port and exfiltrate decrypted v20 cookies — an elevation path relative to reading the SQLite DB directly (which can't decrypt v20 without DPAPI context). Fix direction is `--remote-debugging-pipe` instead of TCP; requires restructuring the CDP client.
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### Bearer token auth
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Every server session generates a random UUID token, written to the state file with mode 0o600 (owner-only read). Every HTTP request must include `Authorization: Bearer <token>`. If the token doesn't match, the server returns 401.
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Every server session generates a random UUID token, written to the state file with mode 0o600 (owner-only read). Every HTTP request that mutates browser state must include `Authorization: Bearer <token>`. If the token doesn't match, the server returns 401.
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This prevents other processes on the same machine from talking to your browse server. The cookie picker UI (`/cookie-picker`) and health check (`/health`) are exempt — they're localhost-only and don't execute commands.
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This prevents other processes on the same machine from talking to your browse server. The cookie picker UI (`/cookie-picker`) and health check (`/health`) are exempt on the local listener — they're 127.0.0.1-bound and don't execute commands. On the tunnel listener nothing is exempt except `/connect`.
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### Cookie security
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BROWSER.md

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### Authentication
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Each server session generates a random UUID as a bearer token. The token is written to the state file (`.gstack/browse.json`) with chmod 600. Every HTTP request must include `Authorization: Bearer <token>`. This prevents other processes on the machine from controlling the browser.
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Each server session generates a random UUID as a bearer token. The token is written to the state file (`.gstack/browse.json`) with chmod 600. Every HTTP request that mutates browser state must include `Authorization: Bearer <token>`. This prevents other processes on the machine from controlling the browser.
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**Dual-listener mode (v1.6.0.0+).** When `pair-agent` activates an ngrok tunnel, the daemon binds a second HTTP socket that serves only `/connect`, `/command` (scoped tokens + a 17-command browser-driving allowlist), and `/sidebar-chat`. The tunnel listener is the only port ngrok forwards; `/health`, `/cookie-picker`, `/inspector/*`, and `/welcome` stay local-only. Root tokens sent over the tunnel return 403. See [ARCHITECTURE.md](ARCHITECTURE.md#dual-listener-tunnel-architecture-v1600) for the full endpoint table.
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SSE endpoints (`/activity/stream`, `/inspector/events`) accept the Bearer token OR the HttpOnly `gstack_sse` session cookie (30-minute stream-scope cookie minted by `POST /sse-session`). The `?token=<ROOT>` query-param auth is no longer supported.
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### Console, network, and dialog capture
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CHANGELOG.md

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# Changelog
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## [1.6.0.0] - 2026-04-21
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## **The token leak in pair-agent sessions is closed by splitting the daemon into two HTTP listeners, not by pretending one port can be two things at once.**
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`pair-agent --client` is gstack's best onboarding moment. One command, a shareable URL, a remote agent driving your browser. It was also the moment we broadcast an unauthenticated `/health` endpoint to the public internet that handed out root browser tokens on any `Origin: chrome-extension://` spoof. @garagon flagged this in PR #1026 and it re-surfaced in a DM. The initial fix (check `tunnelActive` on the `/health` gate) shipped as a patch in review. Codex's outside voice during `/plan-ceo-review` called that approach brittle, and the user pivoted to the architectural fix: physical port separation. That's what this release is.
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When you run `pair-agent --client`, the daemon now binds TWO HTTP listeners. The local port (bootstrap, CLI, sidebar, cookie-picker, inspector) stays on 127.0.0.1 and is never forwarded. The tunnel port serves only `/connect` (pairing ceremony, unauth + rate-limited) and a locked allowlist of browser-driving commands. ngrok forwards only the tunnel port. A caller who stumbles onto your ngrok URL cannot reach `/health`, `/cookie-picker`, `/inspector/*`, or `/welcome` — not because the server denies them, because the HTTP request never arrives at the bootstrap port. Root tokens sent over the tunnel get a 403 with a clear pairing hint.
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The wave also closed three other CVE classes Codex surfaced. `/activity/stream` and `/inspector/events` used to accept the root token in `?token=` query params (URLs leak to logs, referer, history). Now they take a separate view-only 30-minute HttpOnly SameSite=Strict cookie that is NOT valid against `/command`. The `/welcome` handler interpolated `GSTACK_SLUG` into a filesystem path without validation. Fixed with a strict regex. The `/connect` rate limit was 3/min globally, which DOS'd any legitimate pair-agent retry. Loosened to 300/min because setup keys are 24 random bytes (unbruteforceable); the limit is for flood defense, not key guessing. The cookie-import-browser CDP port on Windows is documented as a v20 ABE elevation path with a tracking issue (#1136).
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### The numbers that matter
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| Surface | Before | After |
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|---|---|---|
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| `/health` over tunnel | returns root token to any chrome-extension origin | unreachable (404, wrong port) |
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| `/cookie-picker` over tunnel | HTML embeds the root token | unreachable (404, wrong port) |
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| `/inspector/*` over tunnel | reachable with Bearer | unreachable (404, wrong port) |
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| `/command` over tunnel, root token | executes | 403 with pairing hint |
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| `/command` over tunnel, scoped token | any command | allowlist: 17 browser-driving commands only |
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| `/activity/stream` auth | `?token=<ROOT>` in URL | HttpOnly `gstack_sse` cookie, 30-min TTL, stream-scope only |
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| `/inspector/events` auth | `?token=<ROOT>` in URL | same cookie as /activity/stream |
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| `/connect` rate limit | 3/min (blocked legit retries) | 300/min (flood-only, no pairing DoS) |
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| `/welcome` path traversal | `GSTACK_SLUG="../etc"` interpolates | regex `^[a-z0-9_-]+$`, fallback to built-in |
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| Tunnel auth-denial logging | none | async JSONL to `~/.gstack/security/attempts.jsonl`, rate-capped 60/min |
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| Windows v20 ABE via CDP | undocumented elevation | documented non-goal, tracked as #1136 |
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| Review layer | Verdict | Outcome |
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|---|---|---|
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| `/plan-ceo-review` (Claude) | SELECTIVE EXPANSION | 7 proposals, 7 accepted, critical gap on extension sidebar bootstrap caught |
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| `/codex` (outside voice) | 14 findings | 3 factual errors in the plan fixed, 4 substantive tensions resolved, 2 new CVE classes added |
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| `/plan-eng-review` (Claude) | 5 arch decisions locked | tunnel lifecycle, token scoping, PR #1026 handling, SSE cookie design, route allowlist |
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### What this means for anyone running pair-agent
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Run `pair-agent --client test-agent` on your laptop. Share the ngrok URL with someone. Their agent drives your browser. Your sidebar keeps showing you what they're doing. A stranger who stumbles onto that ngrok URL in the meantime gets 404 on everything except `/connect`, and `/connect` without a setup key goes nowhere. Nothing about the command you type changes.
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### Itemized changes
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#### Added
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- **Dual-listener HTTP architecture.** When a tunnel is active, the daemon binds a dedicated listener on an ephemeral 127.0.0.1 port and points `ngrok.forward()` at it. `/tunnel/start` lazy-binds the listener; `/tunnel/stop` tears it down. Hard-fails on bind error, never falls back to the local port. `BROWSE_TUNNEL=1` startup follows the same pattern. `browse/src/server.ts` ~320 lines.
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- **Tunnel surface filter.** Runs before every route dispatch. 404s paths not on `TUNNEL_PATHS` (`/connect`, `/command`, `/sidebar-chat`). 403s any request carrying the root bearer token with a clear hint. 401s non-/connect requests without a scoped token. Every denial logs to `~/.gstack/security/attempts.jsonl`.
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- **Tunnel command allowlist.** `/command` on the tunnel surface enforces `TUNNEL_COMMANDS` (17 browser-driving commands: `goto`, `click`, `text`, `screenshot`, `html`, `links`, `forms`, `accessibility`, `attrs`, `media`, `data`, `scroll`, `press`, `type`, `select`, `wait`, `eval`). Remote paired agents cannot launch new browsers, configure the daemon, or touch the inspector.
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- **View-only SSE session cookie.** New `browse/src/sse-session-cookie.ts` registry with `POST /sse-session` mint endpoint. 256-bit tokens, 30-minute TTL, HttpOnly + SameSite=Strict. Scope-isolated from the main token registry at the module-boundary level (the module does not import `token-registry.ts`). Prior learning applied: `cookie-picker-auth-isolation`, 10/10 confidence.
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- **Tunnel auth-denial log.** `browse/src/tunnel-denial-log.ts`, async `fs.promises.appendFile` with 60/min rate cap in-process. Prior learning applied: `sync-audit-log-io`, 10/10 confidence.
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- **E2E pairing test.** `browse/test/pair-agent-e2e.test.ts`, 12 behavioral tests against a spawned daemon (BROWSE_HEADLESS_SKIP=1). Verifies `/pair``/connect` → scoped token → `/command` flow, `?token=` query param rejection, `/sse-session` cookie flags. ~220ms, no network.
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- **ARCHITECTURE.md dual-listener contract.** Per-endpoint disposition table (local vs tunnel), tunnel denial log model, SSE cookie scope, N2 non-goal documentation.
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#### Changed
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- **SSE endpoints no longer accept `?token=` in the URL.** `/activity/stream` and `/inspector/events` now take Bearer or the `gstack_sse` cookie. Extension (`extension/sidepanel.js`) fetches the cookie once at bootstrap via `POST /sse-session`, then opens `EventSource` with `withCredentials: true`. The URL never carries a secret.
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- **`/connect` rate limit loosened from 3/min to 300/min.** Setup keys are 24 random bytes; 3/min was a brute-force defense in name only and caused real pairing failures. 300/min handles floods without ever triggering on legitimate use.
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- **`/welcome` GSTACK_SLUG gated on `^[a-z0-9_-]+$`.** Defense-in-depth for a path not exploitable today but trivially mitigable.
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- **`/pair` and `/tunnel/start` probe the cached tunnel via `GET /connect`, not `/health`.** `/health` is no longer reachable on the tunnel surface under the dual-listener design.
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- **`cookie-import-browser.ts` comment corrected.** Previously claimed "no worse than baseline", wrong on Windows with v20 App-Bound Encryption, where the CDP port IS an elevation path. Documented with a tracking issue for the `--remote-debugging-pipe` follow-up.
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#### Fixed
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- **SSRF via download + scrape.** `page.request.fetch` calls in `browse/src/write-commands.ts` now pass through `validateNavigationUrl`. Blocks cloud metadata endpoints (AWS IMDSv1, GCP, Azure), RFC1918 ranges, `file://`. Derived from PR #1029 by @garagon.
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- **Envelope sentinel escape on scoped snapshot.** `browse/src/snapshot.ts` and `browse/src/content-security.ts` now share `escapeEnvelopeSentinels()`. Page content containing the literal envelope delimiter can no longer forge a fake "trusted" block in the LLM context. Derived from PR #1031 by @garagon.
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- **Hidden-element detection across all DOM-reading channels.** Previously only `command === 'text'` ran `markHiddenElements`. Now every DOM channel (`html`, `links`, `forms`, `accessibility`, `attrs`, `media`, `data`, `ux-audit`) surfaces hidden-content warnings in the envelope. Derived from PR #1032 by @garagon.
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- **`--from-file` payload path validation.** `load-html --from-file` and `pdf --from-file` now run `validateReadPath` on the payload path for parity with the direct-API paths. Closes a CLI/API escape hatch for `SAFE_DIRECTORIES`. Derived from PR #1103 by @garagon.
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- **`design/src/serve.ts` interpolated `url.origin` through `JSON.stringify`.** Defensive escape for origin values in served HTML. Contributed by @theqazi (PR #1073 partial).
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- **`scripts/slop-diff.ts` narrows `shell: true` to Windows only.** Matches the platform-specific need without widening the shell-interpretation surface on POSIX. Contributed by @theqazi (PR #1073 partial).
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#### For contributors
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- F1 (dual-listener refactor) is bisected as four commits on the branch: rate-limit loosening, new `tunnel-denial-log` module, the server.ts refactor, and the new source-level test suite. Each commit is independently green. Subsequent wave items rebase onto F1 cleanly.
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- Credits: @garagon (critical bug surface in PR #1026 plus SSRF, envelope, DOM-channel coverage, and --from-file PRs), @Hybirdss (PR #1002 concept, superseded by F1 but informed the policy model), @HMAKT99 (PRs #469 and #472 — both ended up already-landed-on-main; credit for surfacing the issues), @theqazi (2 commits from #1073, skills portion deferred pending internal voice review per CLAUDE.md).
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- Codex-reviewed plan stored at `~/.gstack/projects/garrytan-gstack/ceo-plans/2026-04-21-security-wave-v1.5.2.md`. Eng-review test plan at `~/.gstack/projects/garrytan-gstack/garrytan-garrytan-sec-wave-eng-review-test-plan-*.md`.
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- Non-goal tracked as #1136: switch cookie-import-browser CDP transport from TCP `--remote-debugging-port` to `--remote-debugging-pipe` so the Windows v20 ABE elevation path is closed. Non-trivial (Playwright doesn't expose the pipe transport; needs a minimal CDP-over-pipe client); intentionally deferred from this wave.
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## [1.5.1.0] - 2026-04-20
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## **Three visible bugs in v1.4.0.0 /make-pdf, all fixed.**

CLAUDE.md

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with non-obvious ordering dependencies. The doc exists to prevent the kind of
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silent failures that come from not understanding the cross-component flow.
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**Transport-layer security** (v1.6.0.0+). When `pair-agent` starts an ngrok tunnel,
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the daemon binds two HTTP listeners: a local listener (127.0.0.1, full command
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surface, never forwarded) and a tunnel listener (locked allowlist: `/connect`,
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`/command` with a scoped token + 17-command browser-driving allowlist,
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`/sidebar-chat`). ngrok forwards only the tunnel port. Root tokens over the tunnel
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return 403. SSE endpoints use a 30-minute HttpOnly `gstack_sse` cookie minted via
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`POST /sse-session` (never valid against `/command`). Tunnel-surface rejections go
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to `~/.gstack/security/attempts.jsonl` via `tunnel-denial-log.ts`. Before editing
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`server.ts`, `sse-session-cookie.ts`, or `tunnel-denial-log.ts`, read
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[ARCHITECTURE.md](ARCHITECTURE.md#dual-listener-tunnel-architecture-v1600)
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the module boundary (no imports from `token-registry.ts` into `sse-session-cookie.ts`)
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is load-bearing for scope isolation.
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**Sidebar security stack** (layered defense against prompt injection):
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| Layer | Module | Lives in |

VERSION

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1.5.1.0
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1.6.0.0

browse/src/commands.ts

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'snapshot',
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/**
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* Subset of PAGE_CONTENT_COMMANDS whose output is derived from the
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* live page DOM. These channels can carry hidden elements or
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* ARIA-injection payloads that the centralized envelope wrap alone
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* does not neutralize, so the scoped-token pipeline runs
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* `markHiddenElements` on the page before the read and surfaces any
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* hits as CONTENT WARNINGS to the LLM.
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*
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* `console`, `dialog` intentionally excluded — they read separate
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* runtime state (console capture, dialog events), not the DOM tree.
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*/
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export const DOM_CONTENT_COMMANDS = new Set([
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'text', 'html', 'links', 'forms', 'accessibility', 'attrs',
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'media', 'data', 'ux-audit',
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]);
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/** Wrap output from untrusted-content commands with trust boundary markers */
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export function wrapUntrustedContent(result: string, url: string): string {
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// Sanitize URL: remove newlines to prevent marker injection via history.pushState

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