gstack/browse
gus 01e584253d security: gate domain-skill auto-promote on classifier_score > 0
`browse/src/domain-skill-commands.ts:140` (handleSave) writes
`classifier_score: 0` with the comment "L4 deferred to load-time / sidebar-agent
fills this in on first prompt-injection load." But CLAUDE.md "Sidebar
architecture" documents that sidebar-agent.ts was ripped, and grep for
recordSkillUse + classifierFlagged callers across browse/src/ returns zero hits
outside the module under test.

Net effect: every quarantined skill that survives three benign uses without
flag (`recordSkillUse(... , classifierFlagged: false)` x3) auto-promotes to
`active` and lands in prompt context wrapped as UNTRUSTED on every subsequent
visit to that host. The L4 score that was supposed to gate the promotion was
never written — the production save path puts 0 on disk and nothing later
updates it.

Threat model: a domain-skill body authored by an agent under the influence of
a poisoned page (the new `gstackInjectToTerminal` PTY path runs no L1-L3
either) would lose its auto-promote barrier after three uses. The exploit
isn't single-step but the bar is exactly N=3 prompt-injection-shaped uses on
a hostile page, which is well within reach.

Fix adds a single condition to the auto-promote gate in `recordSkillUse`:

    if (state === 'quarantined' && useCount >= PROMOTE_THRESHOLD &&
        flagCount === 0 && current.classifier_score > 0) {
      state = 'active';
    }

`classifier_score` is set once at writeSkill and never updated. Production
saves it as 0 (handleSave), so the gate stays closed; existing tests that
explicitly pass `classifierScore: 0.1` still auto-promote (the auto-promote
path is preserved for the day L4 is rewired).

Manual promotion via `domain-skill promote-to-global` is unaffected (it goes
through `promoteToGlobal` which has its own state-machine guard at line 337+).

Test: new regression case `does NOT auto-promote when classifier_score is 0
(production handleSave shape)` plants a skill with classifierScore=0 (matches
domain-skill-commands.ts:140), runs three uses without flag, asserts the skill
stays quarantined and readSkill returns null. Negative control: revert the
patch, the test fails with `Received: "active"`. With the patch: 15/15 pass.
2026-05-07 23:22:27 -03:00
..
bin feat: multi-agent support — gstack works on Codex, Gemini CLI, and Cursor (v0.9.0) (#226) 2026-03-19 18:20:50 -07:00
scripts fix: ngrok Windows build + close CI error-swallowing gap (v0.18.0.1) (#1024) 2026-04-16 13:49:04 -07:00
src security: gate domain-skill auto-promote on classifier_score > 0 2026-05-07 23:22:27 -03:00
test security: gate domain-skill auto-promote on classifier_score > 0 2026-05-07 23:22:27 -03:00
PLAN-snapshot-dropdown-interactive.md fix: snapshot -i auto-detects dropdown/popover interactive elements (#845) 2026-04-05 22:57:45 -07:00
SKILL.md v1.27.0.0 feat: /setup-gbrain Path 4 (remote MCP) + brain → artifacts rename (#1351) 2026-05-06 19:37:53 -07:00
SKILL.md.tmpl feat(browse): Puppeteer parity — load-html, screenshot --selector, viewport --scale, file:// (v1.1.0.0) (#1062) 2026-04-18 23:25:33 +08:00