feat(hooks): independent precompact toggle via config + env var

Adds hooks.precompact boolean (default true). Setting false lets /compact
proceed without the pre-compaction mine, independent of save_interval.

Config (~/.mempalace/config.json):
    {"hooks": {"precompact": false}}

Env var (takes precedence):
    MEMPALACE_HOOKS_PRECOMPACT=false

Disabling save_interval does NOT disable precompact and vice versa.

Closes #949. Closes #906.

Author: rusel95

mempalace/config.py

@@ -294,6 +294,39 @@ def hook_silent_save(self):
         """Whether the stop hook saves directly (True) or blocks for MCP calls (False)."""
         return self._file_config.get("hooks", {}).get("silent_save", True)
 
+    @property
+    def hooks_save_interval(self) -> int:
+        """Number of exchanges between auto-save prompts. 0 = disabled.
+
+        Config: {"hooks": {"save_interval": 30}}
+        Env var (takes precedence): MEMPALACE_HOOKS_SAVE_INTERVAL=30
+        """
+        env_val = os.environ.get("MEMPALACE_HOOKS_SAVE_INTERVAL", "").strip()
+        if env_val:
+            try:
+                return max(0, int(env_val))
+            except ValueError:
+                pass
+        val = self._file_config.get("hooks", {}).get("save_interval", 15)
+        try:
+            return max(0, int(val))
+        except (TypeError, ValueError):
+            return 15
+
+    @property
+    def hooks_precompact(self) -> bool:
+        """Whether the precompact hook fires before context compaction. Default: True.
+
+        Config: {"hooks": {"precompact": false}}
+        Env var (takes precedence): MEMPALACE_HOOKS_PRECOMPACT=false
+        """
+        env_val = os.environ.get("MEMPALACE_HOOKS_PRECOMPACT", "").strip().lower()
+        if env_val in ("0", "false", "no", "off"):
+            return False
+        if env_val in ("1", "true", "yes", "on"):
+            return True
+        return bool(self._file_config.get("hooks", {}).get("precompact", True))
+
     @property
     def hook_desktop_toast(self):
         """Whether the stop hook shows a desktop notification via notify-send."""

mempalace/hooks_cli.py

@@ -596,7 +596,17 @@ def hook_stop(data: dict, harness: str):
 
     _log(f"Session {session_id}: {exchange_count} exchanges, {since_last} since last save")
 
-    if since_last >= SAVE_INTERVAL and exchange_count > 0:
+    try:
+        from .config import MempalaceConfig
+        save_interval = int(MempalaceConfig().hooks_save_interval)
+    except Exception:
+        save_interval = SAVE_INTERVAL
+
+    if save_interval == 0:
+        _output({})
+        return
+
+    if since_last >= save_interval and exchange_count > 0:
         _log(f"TRIGGERING SAVE at exchange {exchange_count}")
 
         # Read hook settings from config
@@ -679,6 +689,17 @@ def hook_precompact(data: dict, harness: str):
 
     _log(f"PRE-COMPACT triggered for session {session_id}")
 
+    try:
+        from .config import MempalaceConfig
+        precompact_enabled = MempalaceConfig().hooks_precompact
+    except Exception:
+        precompact_enabled = True
+
+    if not precompact_enabled:
+        _log("Precompact hook disabled via config — skipping mine, allowing compaction")
+        _output({})
+        return
+
     # Capture tool output via our normalize path before compaction loses it
     if transcript_path:
         _ingest_transcript(transcript_path)