Claude Code Memory Compiler

hooks/session-start.py

@@ -0,0 +1,92 @@
+"""
+SessionStart hook - injects knowledge base context into every conversation.
+
+This is the "context injection" layer. When Claude Code starts a session,
+this hook reads the knowledge base index and recent daily log, then injects
+them as additional context so Claude always "remembers" what it has learned.
+
+Configure in .claude/settings.json:
+{
+    "hooks": {
+        "SessionStart": [{
+            "matcher": "",
+            "command": "uv run python hooks/session-start.py"
+        }]
+    }
+}
+"""
+
+import json
+import sys
+from datetime import datetime, timedelta, timezone
+from pathlib import Path
+
+# Paths relative to project root
+ROOT = Path(__file__).resolve().parent.parent
+KNOWLEDGE_DIR = ROOT / "knowledge"
+DAILY_DIR = ROOT / "daily"
+INDEX_FILE = KNOWLEDGE_DIR / "index.md"
+
+MAX_CONTEXT_CHARS = 20_000
+MAX_LOG_LINES = 30
+
+
+def get_recent_log() -> str:
+    """Read the most recent daily log (today or yesterday)."""
+    today = datetime.now(timezone.utc).astimezone()
+
+    for offset in range(2):
+        date = today - timedelta(days=offset)
+        log_path = DAILY_DIR / f"{date.strftime('%Y-%m-%d')}.md"
+        if log_path.exists():
+            lines = log_path.read_text(encoding="utf-8").splitlines()
+            # Return last N lines to keep context small
+            recent = lines[-MAX_LOG_LINES:] if len(lines) > MAX_LOG_LINES else lines
+            return "\n".join(recent)
+
+    return "(no recent daily log)"
+
+
+def build_context() -> str:
+    """Assemble the context to inject into the conversation."""
+    parts = []
+
+    # Today's date
+    today = datetime.now(timezone.utc).astimezone()
+    parts.append(f"## Today\n{today.strftime('%A, %B %d, %Y')}")
+
+    # Knowledge base index (the core retrieval mechanism)
+    if INDEX_FILE.exists():
+        index_content = INDEX_FILE.read_text(encoding="utf-8")
+        parts.append(f"## Knowledge Base Index\n\n{index_content}")
+    else:
+        parts.append("## Knowledge Base Index\n\n(empty - no articles compiled yet)")
+
+    # Recent daily log
+    recent_log = get_recent_log()
+    parts.append(f"## Recent Daily Log\n\n{recent_log}")
+
+    context = "\n\n---\n\n".join(parts)
+
+    # Truncate if too long
+    if len(context) > MAX_CONTEXT_CHARS:
+        context = context[:MAX_CONTEXT_CHARS] + "\n\n...(truncated)"
+
+    return context
+
+
+def main():
+    context = build_context()
+
+    output = {
+        "hookSpecificOutput": {
+            "hookEventName": "SessionStart",
+            "additionalContext": context,
+        }
+    }
+
+    print(json.dumps(output))
+
+
+if __name__ == "__main__":
+    main()