[yujiachen-y]

Change

Adds a Claude Code-style /autocompact command and per-model storage for the automatic compaction trigger, building on contextManagement.compactionTriggerAt (#493). Refs #488.

modelSettings:
  "minimax/MiniMax-M3":
    autoCompactWindow: 400000   # an integer token count above 1, or "auto"
contextManagement:
  compactionTriggerAt: 0.8      # existing global default, unchanged

• Same shape as Claude Code's modelSettings.<model>.autoCompactWindow. The key is the Session's selected provider/model.
• Precedence: the current model's autoCompactWindow, then the global compactionTriggerAt, then the built-in trigger. The selected value is still min()ed with the built-in trigger, so it can only start compaction earlier. auto returns the model to the built-in trigger and ignores the global value. No lower bound (same decision as feat: add contextManagement.compactionTriggerAt to lower the auto-compaction trigger #493). Invalid entries are logged once and ignored.
• /autocompact [auto|<tokens>] uses Claude Code's value grammar (300000, 500k, 1.5M, a bare 100-1000 means thousands) without its 100K floor. Without an argument it shows the current trigger, its share of the window, and its source. Invalid input or no active Session changes nothing. ACP clients get the same command.
• /context now shows the Auto-compact line (trigger and source); it was never rendered because the threshold was hard-coded to null. The trigger is read only when /context is opened, not on status refreshes.
• The automatic compactor keys the setting by the Turn's model selection, not the Pi provider alias, because custom_provider: OAuth routes use the bare provider key as the Pi provider. The read path uses the same agent/model preparation and budget as the compactor, so the shown value is the line compaction actually uses; a save applies from the next model request without a restart.
• Saving reserializes config.yaml with the existing locked writer, so comment formatting is not retained (same as /statusline); documented.

Not included: a launch flag or environment variable override, and any Desktop UI.

Validation

• Checks run and results: pnpm verify (full profile) on 51b963b, darwin: 15 gates passed; test:windows and test:release-package not applicable locally. The capability Vitest group also passed separately (223 files).
• New/changed tests cover the parser and selection (auto-compact-window.test.ts), the per-model writer, compactor selection vs provider alias, production compactor wiring with a real temporary config.yaml (a save changes the very next probe; the read matches the probe boundary), the session-scoped read/write, the host forwarding the model selection, /autocompact in the TUI and ACP, and the /context line.
• Performance: basic. No history construction, serialization, or token-estimation changes; the compactor already read config per call.
• NOT RUN: a live long session against a real model; a real ACP client; Linux/Windows locally (CI covers them).

Publication and contribution checks

• I have permission to contribute these changes under the existing licenses applicable to the changed files/packages; imported material and its provenance are identified and existing notices are preserved.
• No credentials, account data, real user content, internal source history or private review material is included.
• Added/removed source files were reviewed before regenerating release/public-source.json; new tests are declared in test/vitest-suites.json where applicable.
• Shared English/Chinese documentation and capability/verification records are updated where applicable. Mock/offline results are not described as live-service acceptance.

Maintainer handoff

Publication scope or license changes (if any): 7 new source/test files, no license changes.

Shared-source port: complete (internal counterpart exists; the internal version keeps config comments because it has a comment-preserving writer).

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