fix: resolve issues #543, #544, #545, #557 (#558)

* docs: add investigation reports for 5 open GitHub issues

Comprehensive analysis of issues #543, #544, #545, #555, and #557:

- #557: settings.json not generated, module loader error (node/bun mismatch)
- #555: Windows hooks not executing, hasIpc always false
- #545: formatTool crashes on non-JSON tool_input strings
- #544: mem-search skill hint shown incorrectly to Claude Code users
- #543: /claude-mem slash command unavailable despite installation

Each report includes root cause analysis, affected files, and proposed fixes.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix(logger): handle non-JSON tool_input in formatTool (#545)

Wrap JSON.parse in try-catch to handle raw string inputs (e.g., Bash
commands) that aren't valid JSON. Falls back to using the string as-is.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix(context): update mem-search hint to reference MCP tools (#544)

Update hint messages to reference MCP tools (search, get_observations)
instead of the deprecated "mem-search skill" terminology.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix(settings): auto-create settings.json on first load (#557, #543)

When settings.json doesn't exist, create it with defaults instead of
returning in-memory defaults. Creates parent directory if needed.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix(hooks): use bun runtime for hooks except smart-install (#557)

Change hook commands from node to bun since hooks use bun:sqlite.
Keep smart-install.js on node since it bootstraps bun installation.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* chore: rebuild plugin scripts

* docs: clarify that build artifacts must be committed

* fix(docs): update build artifacts directory reference in CLAUDE.md

* test: add test coverage for PR #558 fixes

- Fix 2 failing tests: update "mem-search skill" → "MCP tools" expectations
- Add 56 tests for formatTool() JSON.parse crash fix (Issue #545)
- Add 27 tests for settings.json auto-creation (Issue #543)

Test coverage includes:
- formatTool: JSON parsing, raw strings, objects, null/undefined, all tool types
- Settings: file creation, directory creation, schema migration, edge cases

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* fix(tests): clean up flaky tests and fix circular dependency

Phase 1 of test quality improvements:

- Delete 6 harmful/worthless test files that used problematic mock.module()
  patterns or tested implementation details rather than behavior:
  - context-builder.test.ts (tested internal implementation)
  - export-types.test.ts (fragile mock patterns)
  - smart-install.test.ts (shell script testing antipattern)
  - session_id_refactor.test.ts (outdated, tested refactoring itself)
  - validate_sql_update.test.ts (one-time migration validation)
  - observation-broadcaster.test.ts (excessive mocking)

- Fix circular dependency between logger.ts and SettingsDefaultsManager.ts
  by using late binding pattern - logger now lazily loads settings

- Refactor mock.module() to spyOn() in several test files for more
  maintainable and less brittle tests:
  - observation-compiler.test.ts
  - gemini_agent.test.ts
  - error-handler.test.ts
  - server.test.ts
  - response-processor.test.ts

All 649 tests pass.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* refactor(tests): phase 2 - reduce mock-heavy tests and improve focus

- Remove mock-heavy query tests from observation-compiler.test.ts, keep real buildTimeline tests
- Convert session_id_usage_validation.test.ts from 477 to 178 lines of focused smoke tests
- Remove tests for language built-ins from worker-spawn.test.ts (JSON.parse, array indexing)
- Rename logger-coverage.test.ts to logger-usage-standards.test.ts for clarity

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* docs(tests): phase 3 - add JSDoc mock justification to test files

Document mock usage rationale in 5 test files to improve maintainability:
- error-handler.test.ts: Express req/res mocks, logger spies (~11%)
- fallback-error-handler.test.ts: Zero mocks, pure function tests
- session-cleanup-helper.test.ts: Session fixtures, worker mocks (~19%)
- hook-constants.test.ts: process.platform mock for Windows tests (~12%)
- session_store.test.ts: Zero mocks, real SQLite :memory: database

Part of ongoing effort to document mock justifications per TESTING.md guidelines.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* test(integration): phase 5 - add 72 tests for critical coverage gaps

Add comprehensive test coverage for previously untested areas:

- tests/integration/hook-execution-e2e.test.ts (10 tests)
  Tests lifecycle hooks execution flow and context propagation

- tests/integration/worker-api-endpoints.test.ts (19 tests)
  Tests all worker service HTTP endpoints without heavy mocking

- tests/integration/chroma-vector-sync.test.ts (16 tests)
  Tests vector embedding synchronization with ChromaDB

- tests/utils/tag-stripping.test.ts (27 tests)
  Tests privacy tag stripping utilities for both <private> and
  <meta-observation> tags

All tests use real implementations where feasible, following the
project's testing philosophy of preferring integration-style tests
over unit tests with extensive mocking.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* context update

* docs: add comment linking DEFAULT_DATA_DIR locations

Added NOTE comment in logger.ts pointing to the canonical DEFAULT_DATA_DIR
in SettingsDefaultsManager.ts. This addresses PR reviewer feedback about
the fragility of having the default defined in two places to avoid
circular dependencies.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

src/utils/CLAUDE.md

@@ -0,0 +1,20 @@
+<claude-mem-context>
+# Recent Activity
+
+<!-- This section is auto-generated by claude-mem. Edit content outside the tags. -->
+
+### Jan 5, 2026
+
+| ID | Time | T | Title | Read |
+|----|------|---|-------|------|
+| #30883 | 6:38 PM | 🔵 | Tag-Stripping DRY Violation Analysis | ~152 |
+| #25691 | 4:24 PM | 🔵 | happy_path_error__with_fallback utility logs errors to silent.log and returns fallback values | ~460 |
+| #22310 | 9:46 PM | 🟣 | Complete Hook Lifecycle Documentation Generated | ~603 |
+| #22306 | 9:45 PM | 🔵 | Dual-Tag Privacy System with ReDoS Protection | ~461 |
+| #20407 | 7:20 PM | 🔵 | Tag stripping utilities implement dual-tag privacy system with ReDoS protection | ~415 |
+| #17238 | 11:34 PM | 🔵 | Existing TranscriptParser TypeScript implementation handles nested message structure | ~493 |
+| #14626 | 6:25 PM | 🔵 | Stop Hook Summary Not in Transcript Validator Schema | ~359 |
+| #10019 | 12:14 AM | 🔵 | TranscriptParser Utility: JSONL Parsing with Type-Safe Entry Filtering | ~569 |
+| #6521 | 5:43 PM | 🔵 | Code Review: Enhanced HTTP Logging and Double Entries Bug Fix | ~482 |
+| #4035 | 10:24 PM | 🔵 | logger.ts file exists but is empty | ~220 |
+</claude-mem-context>