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security: suppress /health token when a tunnel is active#1026

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security: suppress /health token when a tunnel is active#1026
garagon wants to merge 1 commit into
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garagon:security/health-token-leak-tunneled-headed

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@garagon garagon commented Apr 16, 2026

Summary

gstack ships pair-agent --client foo as the documented onboarding flow: run it, get a shareable https://…ngrok-free.app URL, send it to the other person, they point their agent at it and start driving your local browser. The flow works because the daemon opens an ngrok tunnel via POST /tunnel/start and stays in headed mode so you can watch the session.

Same daemon exposes /health. That route has an audit history — the v0.15.13.0 wave-3 fix restricted the AUTH_TOKEN field to chrome-extension:// origins so a tunneled instance couldn't leak a bearer that unlocks /command, /read, /upload. Later refactors broadened the gate with an ||:

// browse/src/server.ts around line 1347
...(browserManager.getConnectionMode() === 'headed' ||
    req.headers.get('origin')?.startsWith('chrome-extension://')
    ? { token: AUTH_TOKEN } : {}),

The comment two lines above reads "in headed mode the server is always local, so return token unconditionally." That assumption doesn't hold once pair-agent (or BROWSE_TUNNEL=1) is the default onboarding flow. Headed and tunneled is the explicitly-documented case.

Net effect: any unauthenticated client that knows the tunnel URL can do

curl https://xxx.ngrok-free.app/health | jq -r .token

and receive the root AUTH_TOKEN. That token is accepted by /command (arbitrary JS in the browser), /read (cookies + storage), /upload (file write on the server's disk), and everything else guarded by validateAuth. One-shot remote browser takeover.

This isn't a 0-day against a local install — it's a live vector against anyone who ran pair-agent --client and didn't explicitly stop the tunnel. That's the documented shape of the feature.

Root cause

The || that was added to fix the Playwright-extension-bootstrap case collapsed two very different conditions into one trust boundary:

Condition Localhost-only? Comment
Origin: chrome-extension://<id> Yes (MV3 isolation) The real localhost gate — browsers don't forward this header through a tunnel.
connectionMode === 'headed' No, not anymore True for pair-agent, BROWSE_HEADED=1, every interactive session. Orthogonal to whether a tunnel is open.

The tunnelActive flag at browse/src/server.ts:61 already tracks tunnel state (set by /tunnel/start, cleared by /tunnel/stop and by the liveness probe at line 1505). The /health gate didn't consult it.

Fix

// browse/src/server.ts — after
...(req.headers.get('origin')?.startsWith('chrome-extension://') ||
    (browserManager.getConnectionMode() === 'headed' && !tunnelActive)
    ? { token: AUTH_TOKEN } : {}),
  • Same-origin chrome-extension:// caller still gets the token. MV3 isolation is the localhost guarantee; the token is already inside the extension's process, emitting it back adds no new surface.
  • Headed mode gets the token only while no tunnel is active. Local Playwright development keeps working. The moment pair-agent / BROWSE_TUNNEL=1 / any caller hits POST /tunnel/start, tunnelActive flips to true and /health stops emitting the token, regardless of mode.
  • When the liveness probe at line 1505 clears tunnelActive (ngrok died externally), the local-only branch re-opens automatically.

Reproduction

Before the fix, with the shipped defaults:

# Terminal 1 — gstack operator
BROWSE_HEADED=1 bun run dev serve --tunnel &
# tunnel URL lands in ~/.gstack/tunnel-url, e.g. https://abc.ngrok-free.app

# Terminal 2 — anywhere on the internet
T=$(curl -s https://abc.ngrok-free.app/health | jq -r .token)
# T is the root AUTH_TOKEN, returned with HTTP 200

curl -H "Authorization: Bearer $T" \
     -X POST https://abc.ngrok-free.app/command \
     -d '{"command":"eval","args":["document.cookie"]}'
# → attacker reads cookies from the victim's active tab

After the fix, the same /health request returns {status, mode, uptime, tabs, …} with no token field. /command without the token returns 401.

Sibling review

Grepped every AUTH_TOKEN emission in browse/src/ for the same pattern:

Location Reads AUTH_TOKEN Gate Status
server.ts:~1347 (/health) emits to body was: headed || chrome-extension fixed
server.ts elsewhere used via validateAuth (Authorization header compare) requires client to already have token unaffected
cli.ts, sidebar-agent.ts read from local file / environment, not HTTP local file ACL unaffected

No other HTTP surface emits the raw token. The fix is scoped to the one /health branch.

Tests

browse/test/server-auth.test.ts — source-level guardrails. Kept DB-free and framework-independent, matching the convention in that file.

New regression test

test('/health suppresses the token when a tunnel is active', () => {
  const healthBlock = sliceBetween(SERVER_SRC, "url.pathname === '/health'", "url.pathname === '/connect'");
  expect(healthBlock).toContain('tunnelActive');
  expect(healthBlock).toMatch(/!tunnelActive|tunnelActive\s*===\s*false/);
});

If a future refactor drops the tunnelActive gate this test turns red before the code reaches a reviewer.

Negative control

Reverting browse/src/server.ts to origin/main and rerunning bun test browse/test/server-auth.test.ts:

37 pass
 1 fail

The one failing test is the new one. Applying the fix: 38/38 pass.

Full suite

bun test
# exit 0 — browse + test + skill validation all green

(The "FAIL" rows inside the self-tests of the evals framework are expected by those self-tests — they assert that the framework marks simulated failures correctly.)

What stayed the same

  • Chrome extension bootstrap continues to work (same-origin MV3 case).
  • Local Playwright-extension dev (headed, no tunnel) continues to receive the token.
  • validateAuth remains the primary auth path; this PR only closes the one HTTP response that handed the token out unauthenticated.
  • No changes to tunnelActive lifecycle — the fix reads the existing flag.
  • No new dependencies, no API change.

Files

 browse/src/server.ts            | 19 ++++++++++++-------
 browse/test/server-auth.test.ts | 18 ++++++++++++++++++
 2 files changed, 30 insertions(+), 7 deletions(-)

How to verify

git checkout security/health-token-leak-tunneled-headed
bun install
bun test browse/test/server-auth.test.ts   # 38 pass
bun test                                     # full suite, exit 0

The v0.15.13.0 wave-3 fix that restricted AUTH_TOKEN on /health to
chrome-extension:// origins was later refactored with an OR that
re-allows the token whenever the daemon is in 'headed' connection
mode. Headed mode is the default for every pair-agent and
interactive Playwright session, and 'pair-agent --client' explicitly
opens an ngrok tunnel via POST /tunnel/start. Put those two together
and an unauthenticated remote

  curl https://xxx.ngrok-free.app/health

returns {token: <root>} from the gstack daemon, handing a bearer
token that accepts /command (arbitrary JS), /read (cookie/storage
read), /upload (file write). Full browser takeover from one
ngrok URL.

Root cause is that 'headed' mode was trusted as a proxy for 'local
only'. pair-agent breaks that assumption. Gate the headed branch on
!tunnelActive — the module-level flag already tracks tunnel state
for /tunnel/start and /tunnel/stop. Same-origin chrome-extension://
callers continue to receive the token because MV3 isolation makes
that path localhost-safe regardless of tunnel state.

Tests (browse/test/server-auth.test.ts):
- Existing 'serves token in headed or chrome-extension' test still
  passes (expects headed + chrome-extension:// strings — both still
  present).
- New source-integrity test '/health suppresses the token when a
  tunnel is active' asserts the /health block references
  tunnelActive and contains a negation (!tunnelActive or
  tunnelActive === false). Reverting server.ts to main turns this
  single test red; the fix makes it green.

Reproduction before the fix:
  BROWSE_HEADED=1 bun run dev serve --tunnel &
  curl $(cat ~/.gstack/tunnel-url)/health | jq -r .token
  # → returns AUTH_TOKEN with no auth, from anywhere on the internet.

After the fix:
  # same request returns { status, mode, uptime, tabs, ... } with no
  # token field regardless of connection mode.

No API change. The token is still served for the legitimate cases
(same-origin extension bootstrap, local headed development without
an open tunnel).
garrytan added a commit that referenced this pull request Apr 22, 2026
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>
garrytan added a commit that referenced this pull request Apr 22, 2026
…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>
@garagon
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garagon commented May 1, 2026

Closing — fixed in browse/src/server.ts:1132-1139. The /health response now only includes token when browserManager.getConnectionMode() === 'headed' or the request Origin starts with chrome-extension://. Tunneled requests fall through neither gate, so the token is no longer surfaced over a forwarded port. Different shape than this PR (carve-out instead of unconditional suppression), but the tunnel-leak path the PR was guarding against is closed. Closing as obsolete.

@garagon garagon closed this May 1, 2026
gonnabe88 pushed a commit to gonnabe88/gstack that referenced this pull request May 9, 2026
…0) (garrytan#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 garrytan#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 garrytan#1026 by @garagon — thanks for flagging the critical
  bug that drove the architectural rewrite. The per-request
  isTunneledRequest approach from garrytan#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: garrytan#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 garrytan#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 garrytan#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 garrytan#1136)

Plus the base PRs: SSRF gate (garrytan#1029), envelope sentinel escape (garrytan#1031),
DOM-channel hidden-element coverage (garrytan#1032), --from-file path validation
(garrytan#1103), and 2 commits from garrytan#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 garrytan#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>
RyotaKun pushed a commit to RyotaKun/gstack that referenced this pull request May 18, 2026
…0) (garrytan#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 garrytan#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 garrytan#1026 by @garagon — thanks for flagging the critical
  bug that drove the architectural rewrite. The per-request
  isTunneledRequest approach from garrytan#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: garrytan#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 garrytan#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 garrytan#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 garrytan#1136)

Plus the base PRs: SSRF gate (garrytan#1029), envelope sentinel escape (garrytan#1031),
DOM-channel hidden-element coverage (garrytan#1032), --from-file path validation
(garrytan#1103), and 2 commits from garrytan#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 garrytan#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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