Skip to content

changes.md

Latest commit

 

History

History
95 lines (55 loc) · 7.09 KB

changes.md

File metadata and controls

95 lines (55 loc) · 7.09 KB
Raw

changes.md — compaction

Plugsuit-style Threshold Foundation (2026-04-28)

What changed

  • compaction.ts: Added speculative compaction settings fields (speculativeEnabled, speculativeFraction, speculativeCooldownMs) to CompactionSettings and defaults.
  • extensions/builtin/compaction/policy.ts: Removed the 0.78 OMO threshold floor. Effective threshold now follows the adaptive plugsuit-style tiers directly (0.45/0.50/0.55/0.60/0.65), with yield adjustment clamped to the existing 0.4-0.7 adaptive range.
  • extensions/builtin/compaction/policy.ts: Added SPECULATIVE_FRACTION, shouldStartSpeculativeCompaction(), computeEffectiveKeepRecentTokens(), and isAtHardLimit() for later speculative/emergency phases.
  • settings-manager.ts: Resolved compaction settings now include speculative and restoration fields.
  • extensions/builtin/compaction/index.ts and speculative.ts: Builtin compaction uses resolved settings from ExtensionContext instead of hardcoded defaults for before-turn threshold checks and snapshot preparation.

Why

  • Plugsuit starts compaction much earlier than the OMO 78% floor. Keeping the floor made senpi's auto-compaction late and mostly reactive.
  • Removing the floor alone is unsafe for small context windows because the default keepRecentTokens (20000) can exceed the useful compactable range. The effective keep-recent cap prevents early thresholds from producing empty preparations.
  • Speculative and emergency phases need stable policy functions and settings keys before they can be wired safely.

Why extension system couldn't handle this

  • The policy constants live in the builtin compaction extension and must be shared by unit tests, speculative snapshots, and future emergency pruning.
  • Resolved settings are owned by core SettingsManager; builtin extensions needed a typed ExtensionContext reader to avoid bypassing user settings.json.

Modified upstream files

  • compaction.ts — additive CompactionSettings fields and defaults.
  • settings-manager.ts — resolved setting defaults for new compaction fields.

Expected merge conflict zones

  • LOW: compaction.ts settings interface/defaults.
  • MEDIUM: settings-manager.ts CompactionSettings and getCompactionSettings() if upstream changes settings shape.

Migration notes

  • Preserve the invariant that adaptive threshold and effective keep-recent cap are updated together. Do not reintroduce a hard floor without also proving small-context compaction can still prepare non-empty summaries.

prepareCompaction Rejects Empty Summarization (2026-04-28)

What changed

  • compaction.ts: prepareCompaction() now returns undefined when both messagesToSummarize and turnPrefixMessages are empty.
  • _executeCompaction() (unchanged) reaches its existing "Nothing to compact (session too small)" error path, which surfaces as a clear failure instead of silently invoking the LLM with an empty <conversation> block.

Why

When keepRecentTokens (default 20000) is larger than the total session token count, findCutPoint defaults to the first valid cut point and then findCutPoint's backward scan extends the cut all the way to entry 0 (model_change / thinking_level_change). The result was a preparation with messagesToSummarize: [], turnPrefixMessages: [], and firstKeptEntryId pointing at the very first non-message entry. The new builtin compaction extension then called the LLM with an empty <conversation></conversation> block and the 9-section prompt's R2 rule ("If a section has no content, write 'None.'") forced the model to emit None. for every section. That all-None. summary was persisted as a real compaction entry, destroying the conversation that should have been summarized.

A real reproducer: ~/.senpi/agent/sessions/--Users-yeongyu-local-workspaces-senpi-mono--/2026-04-28T01-50-51-950Z_*.jsonl contains two consecutive compactions on a tiny Kimi K2.6 hello session, both stored as all-None. summaries with tokensBefore of 11527 and 11690.

Why extension system couldn't handle this

prepareCompaction() is core; it computes the cut point, the messages to summarize, and the previous summary. Extensions can override the summary content via session_before_compact, but they cannot decide whether the core preparation step itself should reject the request. Without this guard in core, every extension and the upstream fallback compact() call would have to repeat the same emptiness check.

Modified upstream files

  • compaction.ts — prepareCompaction() returns undefined when there is nothing to summarize.

Expected merge conflict zones

  • LOW: compaction.ts prepareCompaction() is rarely changed upstream. The guard is a small additive check immediately before the final return; conflict resolution is to keep the guard and apply it after upstream's preparation logic computes messagesToSummarize / turnPrefixMessages.

Migration notes

If upstream changes prepareCompaction() to compute additional summary inputs (for example a separate "trailing reminders" array), extend the emptiness guard to include them. The invariant: never return a defined CompactionPreparation whose total summarizable content is empty.

Branch Summarization Routes Through Compaction Hook (2026-04-27)

What changed

  • branch-summarization.ts: generateBranchSummary() now emits session_before_compact with reason: "branch" before the default branch prompt path when an extension runner is provided.
  • branch-summarization.ts: Branch entries are converted into an equivalent CompactionPreparation object for extensions.
  • branch-summarization.ts: Extension { compaction: CompactionResult } responses override the branch summary; { cancel: true } aborts branch summarization.

Why

  • Branch summary was a separate route with a different prompt and no Critical Context section, causing the 9 inconsistencies the user listed.
  • Routing through session_before_compact lets the builtin extension provide one canonical 9-section prompt across all 6 routes.
  • The existing BRANCH_SUMMARY_PROMPT remains the fallback when no extension overrides.

Why extension system couldn't handle this

The branch summarization path did not emit a compaction event before building its default prompt. Extensions can only replace branch summary content after this seam exists in core.

Modified upstream files

  • branch-summarization.ts — emits session_before_compact for branch summaries and accepts extension-provided compaction summaries.

Expected merge conflict zones

  • LOW: branch-summarization.ts is rarely touched upstream. If upstream changes branch summary preparation, keep the hook emission before default prompt construction and update the CompactionPreparation mapping to match the new data flow.

Migration notes

If upstream changes branch summary preparation or adds new branch summary data sources, keep the session_before_compact hook emission before default prompt construction and update the CompactionPreparation mapping to match the new data flow. The BRANCH_SUMMARY_PROMPT fallback must remain intact for sessions without the compaction extension.