flynn/docs/plans/analysis/2026-02-16-codebase-audit-report.md

# Flynn Codebase Audit Report

Date: 2026-02-16  
Scope: Production-risk-first audit of bugs, code improvements, and feature opportunities.

## Remediation Status (2026-02-16)

- ✅ F-001 addressed: chat markdown rendering now sanitizes HTML before DOM insertion in `src/gateway/ui/pages/chat.js` (and legacy `src/gateway/ui/chat.html`).
- ✅ F-006 addressed: inbound HTTP request bodies now enforce a configurable max-size limit (`server.max_request_body_bytes`) with `413 Payload Too Large` responses.
- ✅ F-007 addressed: `ToolExecutor` timeout timer handles are now cleared in `finally`, preventing orphan timers on fast/failed tool calls.
- ✅ F-016 partially addressed: gateway + webhook body readers were consolidated into shared utility `src/utils/httpBody.ts` with size-limit enforcement.
- ✅ F-005 addressed: ESLint JS globals now include `FileReader`, removing UI false-positive lint failures for attachment handling code.
- ✅ F-010 addressed: `session.compact` audit events now emit actual message counts for `messages_before/messages_after` (tokens remain in token fields).
- ✅ F-012 addressed: synthetic repeated-tool nudge no longer emits invalid `tool_result.tool_use_id`; nudge is injected as plain user text guidance.
- ✅ F-009 addressed: gateway now enforces per-connection WebSocket ingress rate limits with deterministic throttle errors and close-on-repeated-violation behavior.
- ✅ F-008 addressed: WhatsApp Chromium launch is now sandboxed by default; no-sandbox mode is behind explicit `whatsapp.no_sandbox: true` opt-in.

## Executive Summary

Current health snapshot:
- `pnpm typecheck`: passing
- `pnpm build`: passing
- `pnpm test:run`: passing (`137/137` files, `1735/1735` tests)
- `pnpm lint`: failing (`148 errors`, `530 warnings`)

Top conclusions:
- A critical Web UI security issue exists in markdown rendering (unsanitized HTML insertion).
- Runtime configuration edits from the settings page appear non-persistent across restart.
- Tool timeout behavior likely allows underlying side effects to continue after timeout.
- Gateway request-body handling and WebSocket ingress controls need abuse protections.
- Lint quality gates are currently broken at scale, reducing CI signal quality.

## Methodology and Scope

Method used:
- Static inspection of core runtime, gateway, UI, and tooling modules.
- Command validation via:
  - `pnpm -s typecheck`
  - `pnpm -s build`
  - `pnpm -s test:run`
  - `pnpm -s lint`

Scope priorities:
1. Security and production reliability
2. Runtime correctness and operational safety
3. Maintainability and engineering throughput
4. New features with measurable user/ops value

Non-goals:
- No code changes in this step
- No architecture rewrite proposals without incremental path

## Findings (Bugs and Risks)

### F-001 Critical: Web UI markdown XSS surface in chat rendering

- Severity: Critical
- Impact: Arbitrary script/HTML injection in browser clients if model/tool output includes malicious markup.
- Evidence:
  - `src/gateway/ui/pages/chat.js:63`
  - `src/gateway/ui/pages/chat.js:610`
- Detail:
  - Assistant/system content is rendered via `marked.parse(...)` then inserted using `innerHTML`.
  - No sanitizer or trusted-types/CSP-backed cleanup is applied before insertion.
- Repro trigger:
  - Assistant response containing HTML payload (for example, event handlers or scriptable tags) in markdown output path.
- Recommended fix:
  - Introduce HTML sanitization (DOMPurify or equivalent) between markdown parse and DOM insertion.
  - Add restrictive CSP for UI surface.
  - Disable raw HTML passthrough in markdown parser if not required.
- Tests to add:
  - Unit tests for sanitization of script/event-handler payloads.
  - Integration test confirming rendered output excludes executable content.

### F-002 High: Settings hook edits are runtime-only and likely not durable

- Severity: High
- Impact: Operators may believe settings were saved permanently when they only changed in-memory state.
- Evidence:
  - `src/gateway/ui/pages/settings.js:148`
  - `src/gateway/handlers/config.ts:135`
- Detail:
  - `config.patch` mutates the active `config` object.
  - No file write-back or persistence layer call is present in handler path.
- Repro trigger:
  - Save hook patterns from UI, restart process, observe values reset to file-backed config.
- Recommended fix:
  - Add persisted config patch pipeline (atomic write + validation + backup).
  - Return `persisted: true|false` in response to avoid misleading UI status.
- Tests to add:
  - Restart-persistence integration test for `hooks.confirm/log/silent`.
  - Error path test for rejected file write with unchanged runtime config.

### F-003 High: Tool timeout does not cancel underlying execution

- Severity: High
- Impact: Timed-out tools can continue executing side effects after caller has received timeout failure.
- Evidence:
  - `src/tools/executor.ts:228`
- Detail:
  - Timeout is implemented with `Promise.race(...)`.
  - No cancellation token/abort path is propagated to long-running tool implementations.
- Repro trigger:
  - Invoke a long-running side-effecting tool, timeout occurs, side effect completes anyway.
- Recommended fix:
  - Add abort signal support to tool contract and propagate cancellation in executor.
  - Enforce cancellation support for high-risk tools (`shell.exec`, `process.start`, web/browser mutating tools).
- Tests to add:
  - Timeout + cancellation conformance tests for cancellable tools.
  - Regression tests verifying no post-timeout side effects.

### F-004 Medium: Lint quality gate is broken and concentrated in key runtime files

- Severity: Medium
- Impact: CI noise, reduced confidence in static analysis, and slower defect detection.
- Evidence:
  - `pnpm -s lint` => `148 errors`, `530 warnings`
  - Error concentration:
    - `src/daemon/models.ts` (90 errors)
    - `src/cli/tui.ts` (25 errors)
    - `src/daemon/routing.ts` (14 errors)
    - `src/gateway/ui/pages/settings.js` (14 errors)
- Detail:
  - Most errors are style/indentation, but gate failure blocks meaningful lint signal.
  - High warning volume includes many `any` and non-null assertions in runtime paths.
- Recommended fix:
  - Two-stage lint recovery:
    1. Clear all error-level violations in top files.
    2. Burn down warning debt in runtime (non-test) modules by policy.
- Tests to add:
  - CI check enforcing `eslint` errors = 0.
  - Secondary threshold check for warning reduction trend.

### F-005 Medium: ESLint browser globals mismatch causes avoidable UI lint failures

- Severity: Medium
- Impact: False-positive lint failures and friction for frontend changes.
- Evidence:
  - `src/gateway/ui/pages/chat.js:127` (`FileReader` not defined in lint)
  - `eslint.config.js` browser globals block does not include `FileReader`.
- Recommended fix:
  - Add missing browser globals used by UI pages, or set UI files to browser env with parser options.
- Tests to add:
  - Lint regression case for UI page using file attachment APIs.

### F-006 High: Request body reader has no size limit (memory DoS risk)

- Severity: High
- Impact: Large POST bodies can force unbounded buffering and memory pressure/crash.
- Evidence:
  - `src/gateway/server.ts:446`
- Detail:
  - `readRequestBody` concatenates all chunks without max-size guard.
  - Path is used by inbound handlers (webhooks/Gmail push route handling).
- Repro trigger:
  - Send very large request body to exposed POST endpoint.
- Recommended fix:
  - Add strict max body size (for example 1 MB default, configurable).
  - Stop reading and destroy request when threshold is exceeded.
  - Return `413 Payload Too Large`.
- Tests to add:
  - Body-under-limit succeeds.
  - Body-over-limit terminates early and returns 413.

### F-007 Medium: Tool timeout race leaves orphan timers

- Severity: Medium
- Impact: Pending timeouts accumulate under load, increasing event-loop overhead.
- Evidence:
  - `src/tools/executor.ts:228`
- Detail:
  - Timeout promise created in `Promise.race` is never cleared when tool resolves quickly.
  - This is distinct from the cancellation gap in F-003.
- Recommended fix:
  - Store timer handle and `clearTimeout(...)` in `finally` after race settles.
- Tests to add:
  - Repeated short tool calls do not grow active timer count.

### F-008 Medium: WhatsApp channel launches Chromium without sandbox

- Severity: Medium
- Impact: Browser compromise has higher blast radius when sandbox is disabled.
- Evidence:
  - `src/channels/whatsapp/adapter.ts:95`
- Detail:
  - Puppeteer launch args include `--no-sandbox` and `--disable-setuid-sandbox`.
- Recommended fix:
  - Default to sandboxed mode.
  - Gate no-sandbox behind explicit high-trust config with warning logs.
- Tests to add:
  - Config test verifies secure default launch args.

### F-009 Medium: Gateway WebSocket ingress lacks rate limiting

- Severity: Medium
- Impact: Abuse can cause resource starvation and model API cost spikes.
- Evidence:
  - `src/gateway/server.ts:291`
- Detail:
  - Incoming WebSocket messages are processed without per-connection throttling.
- Recommended fix:
  - Add token-bucket or leaky-bucket rate limit by connection/session/IP.
  - Add backoff/close behavior for repeated violations.
- Tests to add:
  - Burst traffic triggers throttling and does not starve normal traffic.

### F-010 Medium: Compaction audit event logs token counts in message-count fields

- Severity: Medium
- Impact: Audit accuracy and observability metrics are corrupted.
- Evidence:
  - `src/backends/native/orchestrator.ts:311`
- Detail:
  - `sessionCompact` event uses token counts where message counts are expected.
- Recommended fix:
  - Emit actual pre/post message counts from compaction result.
- Tests to add:
  - Audit event schema/value validation for compaction events.

### F-011 Low: Slack user-name cache has no eviction strategy

- Severity: Low
- Impact: Slow unbounded memory growth in long-running Slack deployments.
- Evidence:
  - `src/channels/slack/adapter.ts:66`
- Recommended fix:
  - Use LRU/TTL cache with maximum entry count.

### F-012 Low-Medium: Synthetic tool nudge uses invalid `tool_use_id`

- Severity: Low-Medium
- Impact: Strict providers may reject tool_result blocks that reference unknown IDs.
- Evidence:
  - `src/backends/native/agent.ts:347`
- Recommended fix:
  - Emit nudge as plain assistant text or tie to valid preceding tool-use ID.

### F-013 Low: Channel adapters duplicate pairing/reset/mention/chunking logic

- Severity: Low
- Impact: Behavior drift and higher maintenance cost across channel implementations.
- Evidence:
  - `src/channels/discord/adapter.ts`
  - `src/channels/slack/adapter.ts`
  - `src/channels/whatsapp/adapter.ts`
- Recommended fix:
  - Extract shared middleware utilities for common inbound/outbound behaviors.

### F-014 Low: ModelRouter listener API has destructive setter footgun

- Severity: Low
- Impact: `setOnTierChange` silently replaces listeners added through append API.
- Evidence:
  - `src/models/router.ts:69`
- Recommended fix:
  - Deprecate/remove setter or explicitly document destructive semantics.

### F-015 Low: Retry defaults classify timeouts as non-retryable

- Severity: Low
- Impact: Reduces resilience for transient timeout failures.
- Evidence:
  - `src/models/retry.ts:29`
- Recommended fix:
  - Remove timeout markers from non-retryable defaults or make behavior configurable.

### F-016 Low: Duplicate request-body utility logic in two modules

- Severity: Low
- Impact: Duplicate maintenance surface and inconsistent future behavior.
- Evidence:
  - `src/gateway/server.ts:446`
  - `src/automation/webhooks.ts:17`
- Recommended fix:
  - Centralize in shared utility with size-limit support.

### F-017 Low: NativeAgent history getter returns mixed mutability semantics

- Severity: Low
- Impact: Caller behavior differs by storage path (by-reference vs copied array).
- Evidence:
  - `src/backends/native/agent.ts:72`
- Recommended fix:
  - Return immutable copy consistently across both paths.

### F-018 Low: Session pruning interval has no jitter

- Severity: Low
- Impact: Multi-instance deployments can synchronize prune spikes.
- Evidence:
  - `src/daemon/index.ts:91`
- Recommended fix:
  - Add randomized jitter window to pruning schedule.

### F-019 Low: `_restoreHistory` no-op when no session is attached

- Severity: Low
- Impact: Sessionless recovery path cannot rollback conversational state.
- Evidence:
  - `src/backends/native/orchestrator.ts:499`
- Recommended fix:
  - Keep explicit in-memory rollback fallback for sessionless mode.

## Code Improvements (Prioritized Backlog)

| Priority | Item | Why | Effort | Dependencies | Acceptance Criteria |
|---|---|---|---|---|---|
| P0 | Secure markdown render pipeline in gateway UI | Closes critical XSS class | M | UI markdown stack + sanitizer lib | All assistant/tool markdown is sanitized before `innerHTML`; security tests pass |
| P0 | Add request-body hard limits in gateway/webhooks | Prevents memory DoS on exposed POST endpoints | S | Shared body reader utility | Oversized payloads are rejected with 413 and no unbounded buffering |
| P0 | Persistent config patch service | Prevents config drift and operator confusion | M | Config loader/writer + schema validation | `config.patch` writes atomically, survives restart, reports persistence status |
| P1 | Tool execution cancellation contract | Prevents post-timeout side effects | L | Tool type updates + executor + tool impls | Timeout triggers cancellation and verified no continued side effects |
| P1 | Fix timeout timer leak in ToolExecutor | Prevents event-loop timer buildup under load | S | ToolExecutor timeout refactor | Timer is always cleared when tool execution settles |
| P1 | WebSocket ingress rate limiting | Mitigates abuse and cost/resource exhaustion | M | Gateway connection/session identity | Excess message bursts are throttled or rejected deterministically |
| P1 | Lint gate restoration program | Recovers static-analysis trust | M | ESLint config + high-error files | `pnpm lint` returns 0 errors on main branch |
| P2 | Reduce runtime `any`/non-null usage | Lowers hidden runtime risk | M | Typed wrappers for channel/model SDKs | Warning count reduced in non-test runtime files with no behavior regressions |
| P2 | Harden WhatsApp browser sandbox defaults | Reduce browser compromise blast radius | M | Channel config schema + adapter launch options | Secure-by-default launch path without `--no-sandbox` |
| P2 | Decompose oversized modules | Improves maintainability and review velocity | L | Module boundary design | `src/daemon/routing.ts`, `src/frontends/tui/minimal.ts`, `src/cli/skills.ts` split into cohesive units |

## Potential New Features (Prioritized Roadmap)

### R-001 Runtime Config Persistence and Versioning
- Problem: Runtime edits are not clearly durable.
- Feature: Versioned config store with atomic patching and rollback.
- User value: Safe live updates with auditability.
- Effort: Medium
- Dependencies: Config writer, schema validator, backup policy.
- Acceptance criteria:
  - Every patch yields version ID.
  - Restart restores latest committed version.
  - Rollback endpoint reverts to previous version safely.

### R-002 Tool Cancellation and Kill-Switch API
- Problem: Timeout without cancellation can leave unsafe side effects.
- Feature: `AbortSignal`-aware tool interface + `tool.cancel` control path.
- User value: Safer automation under failure conditions.
- Effort: Large
- Dependencies: Executor, tool contracts, process/browser tools.
- Acceptance criteria:
  - Cancel request stops active cancellable tools within SLA.
  - Audit events include cancel reason and final state.

### R-003 Security-Hardened Markdown Renderer
- Problem: Model output is untrusted content.
- Feature: Sanitized markdown renderer with strict allowed-tags policy.
- User value: Safe web chat experience by default.
- Effort: Medium
- Dependencies: UI renderer + CSP headers.
- Acceptance criteria:
  - Red-team payload test suite passes.
  - No executable markup reaches final DOM.

### R-004 Quality Health Endpoint
- Problem: No first-class quality telemetry for lint/build/test status.
- Feature: `system.quality` endpoint exposing latest CI/local gate results.
- User value: Faster operator diagnosis and release confidence.
- Effort: Small
- Dependencies: Build metadata collection.
- Acceptance criteria:
  - Endpoint reports lint/typecheck/test/build state with timestamp.
  - Dashboard view consumes and displays status.

### R-005 Config Drift Indicator in Dashboard
- Problem: Runtime and file-backed config can diverge invisibly.
- Feature: Drift warning badge and diff preview in settings page.
- User value: Reduces operational mistakes.
- Effort: Medium
- Dependencies: Persisted config support and hash/diff helper.
- Acceptance criteria:
  - UI shows `in-sync` vs `drifted` state.
  - Operator can preview and reconcile diff.

### R-006 Tool Safety Simulator (Dry-Run Policy Check)
- Problem: Policy/hook changes are hard to validate before production use.
- Feature: Simulate tool calls against policy, autonomy, and hooks without execution.
- User value: Safer policy rollout.
- Effort: Medium
- Dependencies: Tool policy engine and hook decision surface.
- Acceptance criteria:
  - Given tool name/args/context, simulator returns allow/deny + reason chain.
  - Simulation traces can be exported for review.

### R-007 Gateway Abuse Protection Pack
- Problem: WebSocket and POST ingress currently lack explicit anti-abuse controls.
- Feature: Unified ingress controls (body-size limits, per-connection rate limits, adaptive penalties).
- User value: More predictable reliability and lower abuse-induced cost.
- Effort: Medium
- Dependencies: Gateway server, shared request parsing, metrics.
- Acceptance criteria:
  - Oversized payloads rejected early.
  - Rate violations are metered and observable.
  - Healthy traffic retains low latency under synthetic abuse tests.

## 30/60/90-Day Execution Sequence

### 0-30 Days
- Ship markdown sanitization and CSP hardening.
- Add POST body-size limits and shared body reader.
- Restore lint error baseline to zero in mainline.
- Add config patch persistence contract proposal and tests.

### 31-60 Days
- Implement persisted `config.patch` with versioning and rollback.
- Introduce cancellable tool interface and migrate high-risk tools first.
- Implement WebSocket rate limiting and abuse observability.
- Add dashboard drift indicator.

### 61-90 Days
- Complete cancellation coverage across remaining tools.
- Launch quality health endpoint and dashboard integration.
- Add policy simulation tool and operator workflow docs.

## Appendix: Command Evidence

Commands run:

```bash
pnpm -s typecheck
pnpm -s build
pnpm -s test:run
pnpm -s lint
```

Observed outcomes:
- Typecheck/build/test: passing.
- Lint: failing with `148 errors` and `530 warnings`.

Top lint error concentration snapshot:
- `src/daemon/models.ts`: 90 errors
- `src/cli/tui.ts`: 25 errors
- `src/daemon/routing.ts`: 14 errors
- `src/gateway/ui/pages/settings.js`: 14 errors