Function shouldAutoCompact

src/services/compact/autoCompact.ts:189–268

(
  messages: Message[],
  model: string,
  querySource?: QuerySource,
  // Snip removes messages but the surviving assistant's usage still reflects
  // pre-snip context, so tokenCountWithEstimation can't see the savings.
  // Subtract the rough-delta that snip already computed.
  snipTokensFreed = 0,
)

}

export async function shouldAutoCompact(
  messages: Message[],
  model: string,
  querySource?: QuerySource,
  // Snip removes messages but the surviving assistant's usage still reflects
  // pre-snip context, so tokenCountWithEstimation can't see the savings.
  // Subtract the rough-delta that snip already computed.
  snipTokensFreed = 0,
): Promise<boolean> {
  // Recursion guards. session_memory and compact are forked agents that
  // would deadlock.
  if (querySource === 'session_memory' || querySource === 'compact') {
    return false
  }
  // marble_origami is the ctx-agent — if ITS context blows up and
  // autocompact fires, runPostCompactCleanup calls resetContextCollapse()
  // which destroys the MAIN thread's committed log (module-level state
  // shared across forks). Inside feature() so the string DCEs from
  // external builds (it's in excluded-strings.txt).
  if (feature('CONTEXT_COLLAPSE')) {
    if (querySource === 'marble_origami') {
      return false
    }
  }

  if (!isAutoCompactEnabled()) {
    return false
  }

  // Reactive-only mode: suppress proactive autocompact, let reactive compact
  // catch the API's prompt-too-long. feature() wrapper keeps the flag string
  // out of external builds (REACTIVE_COMPACT is ant-only).
  // Note: returning false here also means autoCompactIfNeeded never reaches
  // trySessionMemoryCompaction in the query loop — the /compact call site
  // still tries session memory first. Revisit if reactive-only graduates.
  if (feature('REACTIVE_COMPACT')) {
    if (getFeatureValue_CACHED_MAY_BE_STALE('tengu_cobalt_raccoon', false)) {
      return false
    }
  }

  // Context-collapse mode: same suppression. Collapse IS the context
  // management system when it's on — the 90% commit / 95% blocking-spawn
  // flow owns the headroom problem. Autocompact firing at effective-13k
  // (~93% of effective) sits right between collapse's commit-start (90%)
  // and blocking (95%), so it would race collapse and usually win, nuking
  // granular context that collapse was about to save. Gating here rather
  // than in isAutoCompactEnabled() keeps reactiveCompact alive as the 413
  // fallback (it consults isAutoCompactEnabled directly) and leaves
  // sessionMemory + manual /compact working.
  //
  // Consult isContextCollapseEnabled (not the raw gate) so the
  // CLAUDE_CONTEXT_COLLAPSE env override is honored here too. require()
  // inside the block breaks the init-time cycle (this file exports
  // getEffectiveContextWindowSize which collapse's index imports).
  if (feature('CONTEXT_COLLAPSE')) {
    /* eslint-disable @typescript-eslint/no-require-imports */
    const { isContextCollapseEnabled } =