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LoopGuard Bug Audit Findings

Generated: 2026-07-08 Method: 4 parallel audit agents + manual code review + E2E testing of all 52 Go source files

Summary

Severity Count Confirmed Fixed
Critical 4 4 4
High 8 8 8
Medium 21 21 21
Low 7 7 7
Total 40 40 40

E2E Verification

All fixes verified via live demo scenarios:

  • Spin detection (repeated tools): Fires at 3rd identical call - PASS
  • Spin detection (error echo): Fires at 3rd identical error - PASS
  • Budget warning (80%): Fires at $4.38/$5.00 (88%) - PASS
  • Budget exceeded (100%): Fires at $5.25/$5.00 (105%) with sentinel fallback - PASS
  • Cost tracking: $13.12 accurately computed across 15 calls - PASS
  • Desktop notifications: Sent for warnings and pauses - PASS
  • Session auto-registration: New sessions picked up within 100ms - PASS
  • Env var overrides: LOOPGUARD_BUDGET_PER_SESSION=5 honored - PASS
  • No false positives: Normal sessions run without triggering alerts - PASS
  • Concurrent sessions: Two sessions tracked independently - PASS
  • Graceful shutdown: Clean shutdown with "daemon stopped" logged - PASS
  • Cost tracking accuracy: Non-zero cost computed for sessions - PASS

E2E test suite: 16/16 passed (run via bash demo/test_e2e.sh)

  • Race detector: No races detected (go test -race)

Pass 3 Fixes (integration audit)

  • C3 (Critical): Auto-registered sessions wrote sentinel to wrong directory (decoded path vs storage path), causing enforcement to silently fail while reporting success. Fixed with inferSessionInfo() that derives agent type from discoverer basePath and validates decoded project dir exists before using it.
  • M12 (Medium): applyDefaults prevented YAML from disabling budget limits (zero → default). Fixed to only apply defaults for non-budget structural fields; budget 0 now means "disabled" consistently between YAML and env vars.
  • M7 (Medium): Added RemoveSession() to both Analyzer and BudgetEnforcer for session cleanup.
  • M10 (Medium): Resume API returns HTTP 404 for "session not found" (was 400).
  • M18 (Medium): Codex sessions now set ProjectDir from session path.
  • L1 (Low): Resume detects ambiguous prefix matches and asks for a longer prefix.
  • L3 (Low): HTTP server has read/write/idle timeouts (10s/10s/60s).
  • L4 (Low): Fixed variable shadowing in status.go.
  • L6 (Low): contentToString(nil) returns "" instead of "null".
  • L7 (Low): Tailer handles oversized partial lines with skipToNewline flag to prevent garbled data.

Pass 4 Fixes (final deferred items)

  • M14 (Medium): Kill follow-up now sends SIGKILL to entire process group (-pgid) to clean up orphaned children.
  • M16 (Medium): Custom sessions check liveness via lsof instead of hardcoding Active: true.
  • M17 (Medium): Each custom path gets its own discoverer instance so all directories get fsnotify watches.
  • L2 (Low): History file opened with O_NOFOLLOW to eliminate TOCTOU symlink race window.
  • L5 (Low): StartedAt read from first JSONL line timestamp instead of file ModTime.

Verification

  • Unit tests: All passing
  • Race detector: Clean (go test -race ./...)
  • E2E tests: 16/16 passing
  • All 40 bugs fixed — 0 remaining.

Pass 5 Fixes (live system testing)

  • H6 (High): Resume fails for sentinel-paused sessions (PID=0). enforcer.Resume() required a valid PID for SIGCONT, making sentinel-paused sessions permanently stuck. Fixed: Resume now works without PID — removes sentinel and marks session active.
  • E2E test suite expanded: 19 tests (was 16). Added Test 9: resume flow for sentinel-paused sessions.
  • Verified against real Claude Code sessions: Cost tracking ($0.09 real session), session discovery, StartedAt from JSONL timestamps all confirmed working on live sessions.

Pass 7 Fixes (live enforcement testing)

  • H7 (High): sendSignal sends SIGSTOP to entire process group (-pgid), which freezes the daemon itself when daemon and agent share a process group (same shell session). Fixed: compare target pgid against os.Getpgrp() and fall back to single-PID signal when they match.
  • Live SIGSTOP verified: Real process stopped (state T), SIGCONT resumed it, budget re-triggered immediately (correct behavior — budget limit still in effect).
  • LTF traces verified: Proper JSONL with ltf_version, loop_id, agent, action, cost_usd, result, metadata.
  • History verified: 42 entries, proper JSONL format with timestamps.
  • Adversarial testing verified: Malformed JSONL (binary garbage, empty files, 2MB lines, partial JSON), negative/zero/huge config values, 5 rapid start/stop cycles — no panics, no crashes.

Pass 8 (untested paths)

  • Codex parser end-to-end: Codex session discovered, parsed with CodexParser, cost tracked ($0.07 via gpt-4.1 pricing), spin detection triggered — all verified.
  • CLI edge cases: status offline, resume no-args, resume offline, version, help, config init, config init duplicate, unknown subcommand, stop without service — all return correct errors/output.
  • Stale socket recovery: Daemon starts despite stale socket file.
  • Dual daemon prevention: Second daemon launch rejected with "already running".
  • E2E test suite expanded: 26 tests (was 19). Added stale socket, dual daemon, Codex parser, CLI error handling.

Final verification (all passes combined)

  • Unit tests: all pass
  • Race detector: clean (go test -race ./...)
  • Go vet: clean
  • E2E tests: 26/26 passing
  • Adversarial testing: no crashes on malformed inputs
  • Live enforcement: Real SIGSTOP/SIGCONT verified on live process
  • LTF traces + history: Proper JSONL output verified
  • Real Claude Code sessions: Cost tracking confirmed on live sessions

Critical

C0: Watcher isRelevant filter blocks directory Create events (found in E2E)

  • File: internal/watcher/watcher.go:72-85
  • Status: CONFIRMED | FIXED
  • Description: The isRelevant() check was called BEFORE the directory Create handler. Since directory names don't end in .jsonl, isRelevant returned false, skipping the directory add. New directories created after daemon startup were never watched by fsnotify.
  • Impact: Sessions created in new project directories after daemon start were invisible until the 5s polling fallback kicked in — or never if no tailer existed for the file.
  • Fix: Moved directory Create check before the isRelevant filter.

C1: Foreground daemon never calls Shutdown()

  • File: internal/cli/root.go:71
  • Status: CONFIRMED | FIXED
  • Description: runDaemon() calls d.Run() and returns, but never calls d.Shutdown(). Goroutines leak, LTF file handles leak, watcher is never closed.
  • Impact: Resource leak on every foreground run. Buffered LTF data lost.
  • Fix: Added defer d.Shutdown() after daemon creation.

C2: Shutdown order race — analyzer.Stop() before context cancel

  • File: internal/daemon/daemon.go:142
  • Status: CONFIRMED | FIXED
  • Description: Shutdown() calls analyzer.Stop() (closes done channel) before d.cancel(). During this window, processEvents() can still call analyzer.Process() → emit(), which sees done closed and drops alerts silently.
  • Impact: Alerts lost during shutdown window.
  • Fix: Reordered: cancel() first, then wg.Wait(), then analyzer.Stop(), then cleanup.

High

H0: New sessions not registered until 60s rediscovery cycle (found in E2E)

  • File: internal/daemon/daemon.go:229-260
  • Status: CONFIRMED | FIXED
  • Description: Sessions created after initial discovery were not added to the registry until the 60s rediscovery loop ran. The watcher processed their events and the analyzer detected issues, but executeAlert() couldn't find them in the registry, so all enforcement was skipped.
  • Impact: New sessions were completely unprotected for up to 60 seconds.
  • Fix: Auto-register sessions in processEvents() when the watcher emits events for an unknown session ID.

H1: Budget check returns first violation, masking exceeded limits behind warnings

  • File: internal/analyzer/budget.go:72-90
  • Status: CONFIRMED | FIXED
  • Description: RecordCost() returns the first non-nil BudgetResult. If per-session is at 85% (warning) but per-hour is at 110% (exceeded), only the warning is returned. The exceeded hourly budget is silently ignored.
  • Impact: Session keeps spending past hard limits because the exceeded status is never surfaced.
  • Fix: Collect all results, return the most severe (exceeded > warning).

H2: Non-deterministic prefix match in cost calculator

  • File: internal/analyzer/cost.go:39
  • Status: CONFIRMED | FIXED
  • Description: resolve() iterates a Go map for prefix matching. Map iteration order is random, so "gpt-4.1-mini-2025" could match either "gpt-4.1" ($2/$8) or "gpt-4.1-mini" ($0.40/$1.60) — a 5x pricing error.
  • Impact: Silently wrong cost calculations, budget thresholds crossed at wrong times.
  • Fix: Sort keys by length descending, match longest prefix first.

H3: PID reuse TOCTOU in kill() follow-up goroutine

  • File: internal/enforcer/enforcer.go:108-118
  • Status: CONFIRMED | FIXED
  • Description: After SIGTERM, a goroutine waits 5s then calls validatePID() and killProcess() separately. Between validation and kill, the PID could be recycled to an innocent process.
  • Impact: Could SIGKILL an unrelated process (low probability but catastrophic).
  • Fix: Capture pgid before spawning goroutine; verify process start time before SIGKILL.

H4: Custom discoverer security check bypassed when HOME is unset

  • File: internal/discovery/custom.go:39-46
  • Status: CONFIRMED | FIXED
  • Description: When os.UserHomeDir() fails, home is empty. The check home != "" && !HasPrefix(...) short-circuits to false, allowing any path.
  • Impact: In containers/cron/systemd, the home-dir restriction is silently disabled.
  • Fix: Reject all custom paths when home dir is unavailable.

H5: Lossy decodeProjectDir corrupts paths with hyphens

  • File: internal/discovery/claude.go:85-87
  • Status: CONFIRMED | FIXED
  • Description: All hyphens become path separators. "/my-project" → "/my/project". Documented as lossy but impacts sentinel file placement.
  • Fix: readSessionMeta() extracts the cwd field from the JSONL file (first 20 lines). When present, it overrides the lossy decoded path. Verified on real sessions: /Users/rfirke/Downloads/AI Projects/Loop Engineering now shows correctly.

Medium

M1: Codex parser silently drops Data unmarshal errors

  • File: internal/parser/codex.go:56,70,87
  • Status: CONFIRMED | FIXED
  • Description: json.Unmarshal(entry.Data, &tc) errors are discarded. Malformed events are silently swallowed.
  • Fix: Return errors from unmarshal failures.

M2: Sliding-window slices leak memory

  • File: internal/analyzer/budget.go:67, internal/analyzer/spin.go:215
  • Status: CONFIRMED | FIXED
  • Description: Re-slicing be.hourlyCosts = be.hourlyCosts[trimIdx:] doesn't release the backing array.
  • Fix: Copy to new slice when trimIdx > 0.

M3: seenRequests reset causes token double-counting

  • File: internal/parser/claude.go:85-86
  • Status: CONFIRMED | FIXED
  • Description: Full map reset means previously-seen requestIds are forgotten, causing tokens to be counted twice.
  • Fix: Evict oldest half of entries instead of full reset.

M4: readAndEmit TOCTOU race on tailer creation

  • File: internal/watcher/watcher.go:167-175
  • Status: CONFIRMED | FIXED
  • Description: Check-then-create for tailers is not atomic. Two debouncer callbacks could create duplicate tailers.
  • Fix: Hold the lock across the check-and-create.

M5: AlertKill ignores enforcer.Execute error

  • File: internal/daemon/daemon.go:317
  • Status: CONFIRMED | FIXED
  • Description: If enforcer.Execute(ActionKill, ...) fails, the session is still marked inactive and notifications sent as if it succeeded.
  • Fix: Check error, log it, and only mark inactive if kill succeeded.

M6: Analyzer.Stop() can panic on double close

  • File: internal/analyzer/analyzer.go:165
  • Status: CONFIRMED | FIXED
  • Description: close(a.done) on an already-closed channel panics. No sync.Once guard.
  • Fix: Added sync.Once to guard the close.

M7: Unbounded growth of sessions and warned maps in Analyzer

  • File: internal/analyzer/analyzer.go:49,52
  • Status: CONFIRMED | FIXED
  • Description: No mechanism to remove entries from a.sessions or a.warned when sessions end.
  • Fix: Added RemoveSession() to Analyzer and BudgetEnforcer.

M8: API server goroutine not tracked by WaitGroup

  • File: internal/daemon/daemon.go:110-114
  • Status: CONFIRMED | FIXED
  • Description: API server goroutine not added to wg, so Shutdown() doesn't wait for it.
  • Fix: Added wg.Add(1) and defer wg.Done().

M9: Duplicate socket path implementations

  • File: internal/daemon/daemon.go:329, internal/api/server.go:77
  • Status: CONFIRMED | FIXED
  • Description: Two independent implementations of socket path logic. Could diverge.
  • Fix: Daemon uses api.SocketPath(). Removed daemon.socketPath().

M9b: Auto-registration race can overwrite properly-discovered session (found in pass 2)

  • File: internal/daemon/daemon.go:246, internal/discovery/discovery.go:39
  • Status: CONFIRMED | FIXED
  • Description: processEvents auto-registers unknown sessions via registry.Add, which unconditionally overwrites. If rediscoveryLoop adds a properly-discovered session (with PID) between the Get and Add calls, the proper session is overwritten with a PID-less auto-registered one.
  • Fix: Added Registry.TryAdd() that only adds if session doesn't already exist.

M10: HTTP 400 for all resume errors (should be 404 for not found)

  • File: internal/api/handlers.go:57
  • Status: CONFIRMED | FIXED
  • Description: "session not found" returns 400 instead of 404.
  • Fix: Returns HTTP 404 when error message contains "not found".

M11: Config env var parse errors silently ignored

  • File: internal/config/config.go:100-108
  • Status: CONFIRMED | FIXED
  • Description: fmt.Sscanf errors discarded. User sets LOOPGUARD_BUDGET_PER_SESSION=abc, gets no feedback.
  • Fix: Use strconv.ParseFloat, log warning on parse failure.

M12: YAML null sections zero out default config values

  • File: internal/config/config.go:91
  • Status: CONFIRMED | FIXED
  • Description: A bare budget: key with no values zeros all budget fields, potentially disabling safety limits.
  • Fix: applyDefaults() restores structural defaults (spin thresholds, paths, log level) while allowing budget values of 0 to mean "disabled".

M13: HTTP client has no timeout

  • File: internal/cli/client.go:14
  • Status: CONFIRMED | FIXED
  • Description: CLI commands hang forever if daemon is unresponsive.
  • Fix: Added 10s timeout.

M14: Kill follow-up fails to clean up orphaned child processes

  • File: internal/enforcer/enforcer.go:108
  • Status: CONFIRMED | FIXED
  • Description: If group leader dies but children survive, SIGKILL on leader PID fails, leaving orphans.
  • Fix: SIGKILL follow-up now targets -pgid (entire process group) instead of individual PID.

M15: Sentinel file write follows symlinks

  • File: internal/enforcer/sentinel.go:11
  • Status: CONFIRMED | FIXED
  • Description: os.WriteFile follows symlinks. Attacker could redirect sentinel write to overwrite arbitrary files.
  • Fix: Added Lstat check before WriteFile.

M16: Custom sessions always marked Active:true

  • File: internal/discovery/custom.go:70
  • Status: CONFIRMED | FIXED
  • Description: No liveness check for custom sessions. Stale files reported as active.
  • Fix: Custom sessions use lsof to check if a process has the JSONL file open.

M17: Custom discoverer BasePath() only returns first pattern

  • File: internal/discovery/custom.go:28-32
  • Status: CONFIRMED | FIXED
  • Description: Only the first custom path gets fsnotify watching.
  • Fix: Each custom path creates a separate CustomDiscoverer instance, each returning its own BasePath for watching.

M18: Codex sessions missing ProjectDir

  • File: internal/discovery/codex.go:60
  • Status: CONFIRMED | FIXED
  • Description: ProjectDir is never set for codex sessions, breaking sentinel fallback.
  • Fix: Codex sessions set ProjectDir from the session path directory.

Low

L1: Resume prefix match could match wrong session

  • File: internal/cli/resume.go:27-30
  • Status: CONFIRMED | FIXED
  • Description: First prefix match wins. If multiple sessions share a prefix, wrong one is resumed.
  • Fix: Collects all matches; rejects ambiguous prefixes with a user-facing error listing the matches.

L2: History/emitter TOCTOU symlink check

  • File: internal/daemon/history.go:45, internal/ltf/emitter.go:148
  • Status: CONFIRMED | FIXED
  • Description: Lstat check then OpenFile has a race window for symlink swap.
  • Fix: History file opened with O_NOFOLLOW syscall flag, eliminating the TOCTOU window.

L3: HTTP server has no read/write/idle timeouts

  • File: internal/api/server.go:59
  • Status: CONFIRMED | FIXED
  • Description: A misbehaving client could exhaust file descriptors.
  • Fix: Added ReadTimeout: 10s, WriteTimeout: 10s, IdleTimeout: 60s.

L4: Status variable shadows outer variable

  • File: internal/cli/status.go:51
  • Status: CONFIRMED | FIXED
  • Description: status := "running" shadows outer *api.StatusResponse.
  • Fix: Renamed inner variable to state.

L5: StartedAt set to ModTime not actual session start

  • File: internal/discovery/claude.go:74
  • Status: CONFIRMED | FIXED
  • Description: ModTime reflects last write, not session creation time.
  • Fix: Reads the timestamp from the first JSONL line; falls back to ModTime if parse fails.

L6: AppleScript %q may produce escape sequences osascript doesn't understand

  • File: internal/notify/notify.go:62
  • Status: CONFIRMED | FIXED
  • Description: Go's %q produces \u escapes for non-ASCII; AppleScript may not parse them.
  • Fix: Replaced %q with escapeAppleScript() that only escapes backslashes and double quotes, passing UTF-8 through literally.