@dsh-cc/reasoning-fold

@dsh-cc/reasoning-fold

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Stage-0 reasoning-fold probe: a READ-ONLY llm/stream listener that byte-counts reasoning-delta vs text-delta chunks and captures the terminal usage chunk into a per-session JSONL ledger. Measurement before any behavior change (docs/plans/2026-09-10-reasoning-fold-deepseek.md): the probe is read-only, ledger-only, no behavior change — every chunk passes through untouched, probe failures are swallowed inside the listener, and a ledger failure never degrades a model call. The fold itself (dropping reasoning from the re-send) is a gated, separate Stage-1/2 effort.

How it works

The plugin registers one read-only llm/stream waterfall listener (the only legal read-only shape in a cordis waterfall: it observes chunks while forwarding them from next()). Per call it keeps a local record {provider, model, sessionId, purpose, reasoningBytes, textBytes, usage?} — no shared state across calls — and appends exactly one ledger row in a finally, so an aborted or mid-stream-failed call still records its partial counts. The probe decision is read once per call at its start: a settings flip mid-call never discards an in-flight record.

Byte counts are UTF-8 (Buffer.byteLength), so multibyte reasoning (CJK, emoji) counts by wire bytes. A call with no usage chunk simply omits usage from its row.

Ledger

$DSH_HOME/reasoning-fold/.jsonl, append-only, one JSON line per model call:

{"ts":"2026-09-10T12:00:00.000Z","sessionId":"...","provider":"...","model":"...","purpose":null,"reasoningBytes":1234,"textBytes":567,"usage":{"inputTokens":100,"outputTokens":20,"totalTokens":120,"cacheReadTokens":80,"cacheWriteTokens":0,"reasoningTokens":50}}

purpose is null for ordinary conversation calls and "compaction" / "session-title" for auxiliary ones. All ledger I/O errors are swallowed. Growth is bounded by session count (one file per session); rotate/cap only when reasoning-fold/ exceeds ~10MB or Stage 1 ships.

Usage semantics (harness llm/src/types.ts TokenUsage): inputTokens counts uncached input only; billed input = inputTokens + cacheReadTokens + cacheWriteTokens. Any "re-sent reasoning share of metered input" analysis MUST use that summed billed-input denominator. reasoningTokens is output-side and cannot measure re-send cost.

Settings

Namespace cc-reasoning-fold:

Key	Default	Meaning
probe	true	Master flag. false (read live per call) disables the probe; an in-flight call keeps the decision pinned at its start and still appends its row.

Stage-1 keys below are documented for the future fold — they are inert in Stage 0 and deliberately NOT declared in the settings schema (schema keys without a consumption chain fail the capability manifest audit):

• providers — restrict the probe/fold to matching provider routes.
• head-chars (default 4000), tail-chars (default 2000) — Stage-1 fold window sizes; floor-chars (default 12000) is the minimum reasoning block length for the fold to apply, with the floorChars > headChars + tailChars validation landing at Stage 1.

Shape

Plain cordis plugin (publishes no Service, handoff-store/memory pattern — avoids leakedServices/isolate-key concerns); it registers nothing when the settings provider is absent, probe is false, or dshHomePath is missing (ledger skipped, chunks still pass through). Mounted by packages/preset/cc in the cc-services group.