feat: configurable auto-save interval with independent precompact control

[rusel95]

Closes #494

Summary

Replaces the hardcoded SAVE_INTERVAL = 15 with a user-configurable hooks.save_interval and adds independent hooks.precompact control. This is an alternative to #711 that provides granular frequency control instead of a binary on/off toggle.

Why this is better than #711

	#711 (binary toggle)	This PR (interval + independent precompact)
Stop hook control	auto_save: true/false — all or nothing	save_interval: 30 — any frequency (0 = off)
Precompact	Disabled together with stop hook — data loss risk	Independent toggle — precompact stays on by default
Config duplication	Same check in 2 bash scripts + Python (3 places)	Python only — bash scripts are thin wrappers
User flexibility	"Too noisy? Turn it off entirely"	"Too noisy? Set interval to 50 instead of 15"

Config

// ~/.mempalace/config.json
{
  "hooks": {
    "save_interval": 30,
    "precompact": true
  }
}

Setting	Default	Env var	Effect
save_interval	15	MEMPALACE_HOOKS_SAVE_INTERVAL	Messages between auto-saves. 0 = disabled
precompact	true	MEMPALACE_HOOKS_PRECOMPACT	Block before context compaction. Last chance to save

Key design decision: precompact defaults to true and is controlled separately. Setting save_interval: 0 disables periodic saves but precompact still fires before context is lost. This prevents the data loss scenario where #711's auto_save: false silently disables both hooks.

Changes

File	What
mempalace/config.py	hooks_save_interval and hooks_precompact properties with env var overrides
mempalace/hooks_cli.py	Reads interval from config instead of hardcoded constant; precompact checks its own toggle; shortened block reasons naming exact MCP tools
tests/test_config.py	11 new tests: interval default/config/env/zero/negative, precompact default/disabled/env, independence
tests/test_hooks_cli.py	7 new tests: stop disabled by zero interval, custom intervals (5, 50), precompact disabled/enabled, stop+precompact independence

Test plan

• test_hooks_save_interval_default — default is 15
• test_hooks_save_interval_from_config — reads from config.json
• test_hooks_save_interval_zero_disables — 0 disables stop hook
• test_hooks_save_interval_env_override — env var overrides config
• test_hooks_save_interval_env_zero — env var can set to 0
• test_hooks_save_interval_negative_clamped — negative clamped to 0
• test_hooks_precompact_default — default is true
• test_hooks_precompact_disabled — can be disabled via config
• test_hooks_precompact_env_override — env var overrides
• test_hooks_save_interval_and_precompact_independent — disabling one doesn't affect the other
• test_stop_hook_disabled_by_zero_interval — stop hook passes through
• test_stop_hook_custom_interval — save_interval=5 triggers at 5 messages
• test_stop_hook_custom_interval_not_reached — save_interval=50 doesn't trigger at 15
• test_precompact_disabled_by_config — precompact passes through when disabled
• test_precompact_enabled_by_default — precompact blocks even when stop is disabled
• test_stop_disabled_precompact_still_works — independence verified
• All 59 existing hook/config tests pass (0 regressions)

$ python -m pytest tests/test_config.py tests/test_hooks_cli.py -v
============================== 59 passed in 0.10s ==============================

🤖 Generated with Claude Code

[Naoray]

Strong +1 on this. Hitting the pain point today on 3.3.0:

• Hardcoded SAVE_INTERVAL = 15 fires way too often on conversational/admin sessions — had to locally patch to 50.
• hooks.precompact being independently toggleable is the right call. The current always-block precompact (prior to fix(hooks): stop precompact hook from blocking compaction (#856, #858) #863 / still in 3.3.0 release) permanently broke /compact in long sessions; config toggle would let users opt out without losing the stop-hook save.

The design choice of keeping precompact: true by default when save_interval: 0 is exactly right — no silent data loss. #711's binary toggle would conflate these.

Would love to see this land. Happy to smoke-test against 3.3.0 if useful.

[rusel95]

Pushed cleanup (c2c2f6a):

• Removed 5 stray personal notes files that got in via a local merge conflict. PR diff is now minimal: .gitignore, config.py, hooks_cli.py, plus tests.
• All 84 tests pass locally (pytest tests/test_config.py tests/test_hooks_cli.py).
• Mergeable against develop, no conflicts.

Re-pinging because this PR addresses several now-filed bugs

The independent hooks.precompact toggle is the reason I split it from save_interval in the first place — it directly covers the recently reported PreCompact blocking incidents:

• PreCompact hook blocks indefinitely — no escape condition #949 — PreCompact hook blocks indefinitely (no escape)
• PreCompact hook blocks compaction permanently — should use systemMessage instead #941 — PreCompact should use systemMessage instead of blocking
• preCompact hook prevents compacting when context limit is reached in claude code #906 — PreCompact prevents compaction at context limit
• Compaction Blocking #955 — Compaction Blocking
• Feature Request: Add a "Silent Mode" / Background Processing for the Stop Hook (Auto-save) #494 — Silent Mode / Background Processing (originally filed)

With this PR:

• save_interval: 50 quiets the stop-hook without silencing data-preservation paths.
• precompact: false lets users disable precompact independently if it's misbehaving — without also losing the periodic save (or vice versa).
• That's the key difference vs. feat(hooks): tune stop-hook cadence via env vars (MEMPAL_SAVE_INTERVAL / MEMPAL_STOP_HOOK_DISABLE) #985 (env-var-only, no precompact control) and feat: add hooks.auto_save config toggle (silent mode) #711 (binary all-or-nothing).

Design note for @igorls @bensig @milla-jovovich: the two controls live in config.py (properties) with env-var overrides, so both CLI config-file and per-session env-var workflows work. No new bash-side logic — the hooks stay thin wrappers.

Happy to rebase or adjust naming (e.g. MEMPALACE_HOOKS_SAVE_INTERVAL → MEMPAL_SAVE_INTERVAL to match #985's naming) if that smooths merge.