feat(hooks): implement Stop hook enhancement for Phase 4

- Add session_analyzer.py for transcript analysis and uncaptured memory detection
- Add stop_handler.py with session analysis, capture prompts, and index sync
- Update stop.py wrapper to delegate to new handler module
- Export SessionAnalyzer and TranscriptContent from hooks module
- Update PROGRESS.md with Phase 4 completion notes

Phase 4 complete: All 5 tasks done (20/27 total tasks, 74%)

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

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

Author: zircote

docs/spec/active/2025-12-19-hook-based-memory-capture/PROGRESS.md

@@ -4,7 +4,7 @@ format_version: "1.0.0"
 project_id: SPEC-2025-12-19-001
 project_name: "Hook-Based Memory Capture"
 project_status: in-progress
-current_phase: 4
+current_phase: 5
 implementation_started: 2025-12-19T00:00:00Z
 last_session: 2025-12-19T00:00:00Z
 last_updated: 2025-12-19T00:00:00Z
@@ -42,11 +42,11 @@ This document tracks implementation progress against the spec plan.
 | 3.4 | Create UserPromptSubmit Hook Handler | done | 2025-12-19 | 2025-12-19 | Created `hooks/user_prompt_handler.py` |
 | 3.5 | Format Capture Suggestions | done | 2025-12-19 | 2025-12-19 | XML formatter in handler via XMLBuilder |
 | 3.6 | Register UserPromptSubmit Hook | done | 2025-12-19 | 2025-12-19 | Updated hooks.json, created wrapper |
-| 4.1 | Implement Session Analyzer | pending | | | Transcript analysis |
-| 4.2 | Detect Uncaptured Memories | pending | | | Filter already-captured |
-| 4.3 | Enhance Stop Hook Handler | pending | | | Update hooks/stop.py |
-| 4.4 | Implement Capture Prompt | pending | | | Format uncaptured content prompt |
-| 4.5 | Index Synchronization | pending | | | Sync on session end |
+| 4.1 | Implement Session Analyzer | done | 2025-12-19 | 2025-12-19 | Created `hooks/session_analyzer.py` |
+| 4.2 | Detect Uncaptured Memories | done | 2025-12-19 | 2025-12-19 | Integrated in SessionAnalyzer with novelty filtering |
+| 4.3 | Enhance Stop Hook Handler | done | 2025-12-19 | 2025-12-19 | Created `hooks/stop_handler.py` |
+| 4.4 | Implement Capture Prompt | done | 2025-12-19 | 2025-12-19 | XML formatting in stop_handler |
+| 4.5 | Index Synchronization | done | 2025-12-19 | 2025-12-19 | SyncService integration in stop_handler |
 | 5.1 | Unit Tests - Hook Services | pending | | | XMLBuilder, ContextBuilder, etc. |
 | 5.2 | Unit Tests - Hook Handlers | pending | | | Hook script tests |
 | 5.3 | Integration Tests | pending | | | End-to-end flows |
@@ -64,7 +64,7 @@ This document tracks implementation progress against the spec plan.
 | 1 | Core Hook Infrastructure | 100% | done |
 | 2 | SessionStart Context Injection | 100% | done |
 | 3 | Capture Signal Detection | 100% | done |
-| 4 | Stop Hook Enhancement | 0% | pending |
+| 4 | Stop Hook Enhancement | 100% | done |
 | 5 | Testing & Documentation | 0% | pending |
 
 ---
@@ -151,3 +151,27 @@ This document tracks implementation progress against the spec plan.
   - `mypy` - No issues found in 11 source files
   - `pytest` - 910 tests passed
 - Ready for Phase 4: Stop Hook Enhancement
+
+### 2025-12-19 - Phase 4 Complete
+- **Phase 4 completed**: All 5 tasks done
+- Created `src/git_notes_memory/hooks/session_analyzer.py`:
+  - `SessionAnalyzer` class for parsing and analyzing session transcripts
+  - `TranscriptContent` frozen dataclass for parsed transcript data
+  - Pattern-based user message extraction from transcripts
+  - Novelty filtering to skip already-captured content
+  - Confidence-based ranking and result limiting
+- Created `src/git_notes_memory/hooks/stop_handler.py`:
+  - Full Stop hook handler with session analysis
+  - Uncaptured content detection via SessionAnalyzer integration
+  - XML-formatted output for uncaptured memories via XMLBuilder
+  - Index synchronization via SyncService.reindex(full=False)
+  - Configuration support: `stop_enabled`, `stop_prompt_uncaptured`, `stop_sync_index`
+  - Non-blocking error handling (exit 0 on all paths)
+- Updated `hooks/stop.py` wrapper script:
+  - Delegates to stop_handler module
+  - Graceful fallback if library not installed
+- All quality gates passed:
+  - `ruff check` - All checks passed
+  - `mypy` - No issues found in 13 source files
+  - `pytest` - 910 tests passed
+- Ready for Phase 5: Testing & Documentation

hooks/stop.py

@@ -1,72 +1,49 @@
 #!/usr/bin/env python3
-"""Hook: Sync memory index on session end.
-
-This hook performs a lightweight incremental sync of the memory index
-when a Claude Code session ends. This ensures any memories captured
-during the session are properly indexed for future retrieval.
+"""Hook: Process session end with uncaptured content detection and index sync.
+
+This hook performs session-end tasks:
+1. Analyzes session transcript for uncaptured memorable content
+2. Prompts user to capture worthy content (if configured)
+3. Synchronizes the memory index
+
+Environment Variables:
+    HOOK_ENABLED: Master switch for hooks (default: true)
+    HOOK_STOP_ENABLED: Enable this hook (default: true)
+    HOOK_STOP_PROMPT_UNCAPTURED: Prompt for uncaptured content (default: true)
+    HOOK_STOP_SYNC_INDEX: Sync index on session end (default: true)
+    HOOK_DEBUG: Enable debug logging (default: false)
+
+Exit codes:
+    0 - Success (non-blocking)
 """
 
 from __future__ import annotations
 
-import json
 import sys
 
 
-def sync_index() -> dict:
-    """Perform incremental index sync.
+def main() -> None:
+    """Main hook entry point.
 
-    Returns dict with sync result.
+    Delegates to the stop_handler module for actual processing.
+    Falls back gracefully if the library is not installed.
     """
     try:
-        from git_notes_memory import get_sync_service
-
-        sync = get_sync_service()
-        stats = sync.incremental_sync()
-
-        return {
-            "success": True,
-            "stats": {
-                "scanned": stats.get("scanned", 0),
-                "added": stats.get("added", 0),
-                "updated": stats.get("updated", 0),
-            }
-        }
+        from git_notes_memory.hooks.stop_handler import main as handler_main
 
+        handler_main()
     except ImportError:
-        # Library not installed, skip silently
-        return {"success": True, "skipped": True}
-    except Exception as e:
-        return {
-            "success": False,
-            "error": str(e)
-        }
-
-
-def main() -> None:
-    """Main hook entry point."""
-    # Read hook input from stdin (may be empty for stop hook)
-    try:
-        input_data = json.load(sys.stdin)
-    except (json.JSONDecodeError, ValueError):
-        input_data = {}
-
-    # Perform sync
-    result = sync_index()
-
-    # Output result
-    output = {"continue": True}
+        # Library not installed, exit silently (non-blocking)
+        import json
 
-    if result.get("skipped"):
-        # Silently skip if library not installed
-        pass
-    elif result.get("success"):
-        stats = result.get("stats", {})
-        if stats.get("added", 0) > 0 or stats.get("updated", 0) > 0:
-            output["message"] = f"Memory index synced: +{stats.get('added', 0)} new, ~{stats.get('updated', 0)} updated"
-    else:
-        output["warning"] = f"Memory sync failed: {result.get('error', 'Unknown error')}"
+        print(json.dumps({"continue": True}))
+        sys.exit(0)
+    except Exception:
+        # Any unexpected error, exit silently (non-blocking)
+        import json
 
-    print(json.dumps(output))
+        print(json.dumps({"continue": True}))
+        sys.exit(0)
 
 
 if __name__ == "__main__":

src/git_notes_memory/hooks/__init__.py

@@ -53,6 +53,9 @@
     "CaptureDecider",
     "CaptureDecision",
     "CaptureAction",
+    # Session Analysis
+    "SessionAnalyzer",
+    "TranscriptContent",
     # Project Detection
     "detect_project",
 ]
@@ -131,6 +134,16 @@ def __getattr__(name: str) -> object:
 
         return CaptureAction
 
+    # Session Analysis
+    if name == "SessionAnalyzer":
+        from git_notes_memory.hooks.session_analyzer import SessionAnalyzer
+
+        return SessionAnalyzer
+    if name == "TranscriptContent":
+        from git_notes_memory.hooks.session_analyzer import TranscriptContent
+
+        return TranscriptContent
+
     # Project Detection
     if name == "detect_project":
         from git_notes_memory.hooks.project_detector import detect_project