feat(core): add microcompaction for idle context cleanup (#3006)

* feat(core): add microcompaction for idle context cleanup

Clear old tool result content from chat history when the user returns
after an idle period (default 60 min). Replaces functionResponse output
with a sentinel string for compactable tools (read_file, shell, grep,
glob, web_fetch, web_search, edit, write_file), keeping the N most
recent results intact (default 5). Runs before full compression so it
can shed tokens cheaply without an API call.

- Time-based trigger reuses lastApiCompletionTimestamp from thinking cleanup
- Per-part counting so keepRecent applies to individual tool results
  even when batched in parallel
- Preserves tool error responses (only clears successful outputs)
- Configurable via settings.json (context.microcompaction) with env var
  overrides for E2E testing
- Enabled by default

* refactor(config): unify idle cleanup settings under clearContextOnIdle

Consolidate thinking block cleanup and tool results microcompaction
config into a single `context.clearContextOnIdle` settings group:

  {
    "context": {
      "clearContextOnIdle": {
        "thinkingThresholdMinutes": 5,
        "toolResultsThresholdMinutes": 60,
        "toolResultsNumToKeep": 5
      }
    }
  }

- Use -1 on either threshold to disable that cleanup (no enabled bool)
- Remove separate `microcompaction` and `gapThresholdMinutes` settings
- Thinking cleanup: 5 min default (unchanged)
- Tool results cleanup: 60 min default
- Preserve tool error responses (only clear successful outputs)

* feat(vscode-ide-companion): add clearContextOnIdle settings configuration

- Add gapThresholdMinutes settings for thinking blocks, tool results, and retention count
- Remove deprecated gapThresholdMinutes from root settings level

This reorganizes the context clearing settings into a dedicated clearContextOnIdle object with configurable thresholds for thinking blocks and tool results.

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

* fix(core): restrict microcompaction to user-initiated messages only

Move microcompactHistory() inside the UserQuery/Cron guard so model
latency during tool-call loops doesn't count as user idle time.

* docs: update settings docs for clearContextOnIdle config rename

Replace stale `context.gapThresholdMinutes` entry with the new
`context.clearContextOnIdle.*` settings group introduced in the
microcompaction feature.

* fix(core): address review comments on microcompaction PR

- Guard against NaN in toolResultsNumToKeep with Number.isFinite()
- Report effective keepRecent (after Math.max) in meta, not raw config
- Fix comment to mention cron messages alongside user messages

---------

Co-authored-by: Qwen-Coder <qwen-coder@alibabacloud.com>

packages/cli/src/config/config.ts

@@ -1068,8 +1068,8 @@ export async function loadCliConfig(
     },
     telemetry: telemetrySettings,
     usageStatisticsEnabled: settings.privacy?.usageStatisticsEnabled ?? true,
+    clearContextOnIdle: settings.context?.clearContextOnIdle,
     fileFiltering: settings.context?.fileFiltering,
-    thinkingIdleThresholdMinutes: settings.context?.gapThresholdMinutes,
     checkpointing:
       argv.checkpointing || settings.general?.checkpointing?.enabled,
     proxy: