Stale Synapse Chrome bridge debugger permission can still trigger browser infobar

[ChrisRoyse]

Parent/context: #1220. Related: #1249, #1253, #1254.

Problem

The operator reports the Chrome infobar/message that Synapse Chrome Bridge started debugging this browser is still appearing in the already-open normal Chrome browser. That banner changes the browser viewport/layout and throws off AI clicks, so Synapse must automatically prevent it or fail closed before any normal-browser work can trigger it.

Initial root-cause finding

The repo manifest is debugger-free, and the service worker rejects attach-capable commands. However, setup currently checks the live Chrome profile row for stale Synapse active permissions and only records stale nativeMessaging, not stale debugger. A previously-loaded Synapse bridge can therefore still have active_api containing debugger in Chrome profile state and remain capable of triggering the Chrome debugger infobar under the Synapse extension name.

Expected

The normal authenticated Chrome bridge must never have or use debugger/nativeMessaging permission. Setup/health must detect stale live Synapse debugger permission as a fatal repair state, guide cdp_bridge_reload/extension reload, and prevent normal browser commands from proceeding while the stale debugger-capable Synapse bridge is active.

Manual FSV plan

Use real wired mcp__synapse tools only: health/tool surface, act_run_shell profile/policy readback, installer/setup readback, cdp_bridge_reload if available, then cdp_open_tab/cdp_target_info/target_act on the already-open Chrome browser. Before/after SoTs include Chrome profile permission rows, ExtensionSettings policy, health bridge identity/stale fields, visible window/OCR for the infobar text, event log rows, target claims, and cleanup. Edges: stale debugger row detection, clean tabs-only row, malformed/absent profile row, attach-capable command refusal with no Chrome command queued.

No GitHub Actions/CI. Commits must include [skip ci].

[ChrisRoyse]

RESOLVED - manual real-MCP FSV

Commit: 22d4d0a1 fix(chrome): block debugger infobar hazards (#1255) [skip ci]

Source of Truth

• Real Synapse MCP daemon: mcp__synapse.health PID 73388, bind 127.0.0.1:7700, tool_count 97, tool surface SHA 2739ff4696bc96018d5ca4b2da5328e1a8158872e74766fa51cffa2c10489de1.
• Chrome bridge registration: extension build synapse-chrome-bridge-2026-06-18-strict-hwnd-target-v1, SHA 97441613be8ff1883e9c24a22c231bfd23f14b505e0bff54a7a8282281d3f55d, stale=false.
• Chrome profile/policy files: Profile 5\Secure Preferences and HKCU\Software\Policies\Google\Chrome\ExtensionSettings.
• Physical UI/window state: window_list, read_text, target_claim_status, and daemon-tool-events.jsonl.

Before

• Health reported chrome_bridge.status=blocked, tab_control_available=false, external_chrome_popup_risk_blocking=true.
• Profile readback: Synapse extension active API was alarms,tabs,scripting; stale granted permissions still included debugger,nativeMessaging. Claude extension fcoeoabgfenejglbffodgkkbkcdhcgfn was runtime-enabled with active/granted debugger,nativeMessaging.
• Policy readback remained {"fcoeoabgfenejglbffodgkkbkcdhcgfn":{"installation_mode":"allowed","blocked_permissions":[]}}.
• Browser readback: one Chrome HWND 2427400, title Calyx | Store meaning, not tokens - Google Chrome; target claims 0; OCR did not contain debugging this browser or started debugging.

Trigger + Expected

• Trigger: real mcp__synapse.cdp_open_tab({ window_hwnd: 2427400, url: "data:text/html,<title>issue1255-happy</title>..." }).
• Expected: refuse before any Chrome command is queued, with A11Y_CDP_DEBUGGER_WARNING_UNSUPPRESSED, because the external debugger/nativeMessaging hazard is unsuppressed.

After

• Trigger returned A11Y_CDP_DEBUGGER_WARNING_UNSUPPRESSED with before queueing any Chrome command.
• Separate window/claim readbacks stayed stable: one Chrome HWND 2427400, same title, target claims 0.
• Bounded header OCR still contained no Chrome debugging infobar text.
• daemon-tool-events.jsonl contained cdp_open_tab error rows with A11Y_CDP_DEBUGGER_WARNING_UNSUPPRESSED and before queueing any Chrome command.

Edge Cases

1. Empty URL: cdp_open_tab(window_hwnd=2427400, url="") refused with A11Y_CDP_DEBUGGER_WARNING_UNSUPPRESSED before Chrome work.
2. Structurally invalid HWND: cdp_open_tab(window_hwnd=0, ...) refused with TARGET_WINDOW_NOT_FOUND before Chrome work.
3. Fake/unowned target: cdp_target_info(window_hwnd=2427400, cdp_target_id="chrome-tab:issue1255-fake-target") refused with ACTION_TARGET_INVALID.
4. Installer/policy edge: real mcp__synapse.act_run_shell running scripts\install-synapse-chrome-debugger.ps1 returned ok=False, chrome_policy_popup_shield.blocking=True, external_popup_risk_blocks_popup_free_commands=True, and SYNAPSE_CHROME_POLICY_POPUP_SHIELD_WRITE_DENIED.

Supporting Checks

• cargo fmt --check
• node --check extensions\synapse-chrome-debugger\service_worker.js
• PowerShell parser for scripts\install-synapse-chrome-debugger.ps1
• git diff --check
• cargo check -p synapse-mcp --bin synapse-mcp
• cargo test -p synapse-mcp --bin synapse-mcp external_popup_risk -- --nocapture
• cargo test -p synapse-mcp --bin synapse-mcp chrome_bridge_health -- --nocapture
• cargo test -p synapse-mcp --bin synapse-mcp target_act_read_routes -- --nocapture
• Local pre-push hook ran cargo clippy --workspace --all-targets and completed green with existing warnings.

No GitHub Actions/CI were used. FSV was manual via real Synapse MCP tools plus separate physical SoT readbacks.

[ChrisRoyse]

Closing after manual real-MCP FSV evidence in #1255 (comment). No GitHub Actions/CI used.

[ChrisRoyse]

Close-marker pushed: \773b47b7 chore: close #1255 [skip ci]\. Readback after close: #1255 state CLOSED. Repo main is kept current; no GitHub Actions/CI used.

[ChrisRoyse]

REOPENED 2026-06-19: operator reports the visible Chrome banner text still appears: 'Synapse Chrome Bridge started debugging this browser'. Treat prior #1255/#1249/#1260 mitigation as insufficient. New acceptance: the normal authenticated Chrome profile must be structurally unable to run a Synapse Chrome Bridge build with debugger/nativeMessaging capability or stale build identity; setup/health must auto-shield or fail closed before any bridge command, and manual real-MCP FSV must verify health/window/process/policy SoTs before/after plus happy path and >=3 edges. No GitHub Actions/CI.