195 lines
12 KiB
Markdown
195 lines
12 KiB
Markdown
# Telemetry
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English | [中文](telemetry.zh.md)
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Outbound session reporting is split as a [capability seam](../capability-seams.md): the Service Definition and capture coordinator ([dsh-session-telemetry](../../packages/session/session-telemetry), `ctx.telemetry`) own the capture points, fixed chunk projection, `telemetry/record` redaction waterfall, handoff cursor, and minimal backend contract; the Service provider a deployment loads ([dsh-session-telemetry-otel](../../packages/session/session-telemetry-otel)) is the OpenTelemetry JS SDK's log pipeline configured verbatim. It is one optional capability, not part of the agent-loop spine, and nothing here reaches a model request. The boundary axiom — the harness's aspect ends at `emit()`; batching, retry, queueing, and loss policy belong to the reporting SDK — and the rejected alternatives are pinned in the [revival Agent Note](../../.agents/notes/implemented/feature/2026-07-23-session-telemetry-otel-revival.md); the capture points, cursor, and projection contracts live in the [Service Definition README](../../packages/session/session-telemetry/README.md).
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Source: [`packages/session/session-telemetry/src/index.ts`](../../packages/session/session-telemetry/src/index.ts)
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## The logical record
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```ts type-equiv
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/**
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* Severity of a telemetry record, pre-mapped at capture so a receiver can
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* alert with zero configuration: `error` for events whose own outcome flag
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* says so (the tool-result block's `isError`, `turn/end` error reasons) and for
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* `agent-error` operational records. Captured events otherwise default to
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* `info`; `warn` remains available to `telemetry/record` policies and
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* backends.
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*/
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type TelemetrySeverity = 'info' | 'warn' | 'error'
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```
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```ts type-equiv
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/**
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* One logical record handed to a backend — the capture contract's whole outbound
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* vocabulary. Ledger records mirror session-log events one-to-one;
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* operational records (`channel: 'ops'`) carry the two signals with no log
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* home (`agent-error`, `shutdown`) and deliberately omit `event.seq`-style
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* identity so they can never be mistaken for ledger rows.
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*/
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interface TelemetryRecord {
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/** Ledger (session-log mirror) or ops (operational signal) channel; backends keep the two under separate instrumentation scopes. */
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channel: 'ledger' | 'ops'
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/** Unix epoch milliseconds — the source event's append time for ledger records, the emission time for ops records. */
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time: number
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/** Pre-mapped alerting severity; see {@link TelemetrySeverity}. */
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severity: TelemetrySeverity
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/**
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* Identity attributes, deliberately minimal: ledger records carry
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* `session.id`, `event.type`, `event.seq`, plus `session.cwd` /
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* `session.parent_id` / `session.seed_length` when the header has them;
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* ops records carry `telemetry.op`, `session.id`, and (for `agent-error`)
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* `agent.id`, `turn`, `step`, `error.name`. Anything recoverable from the
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* body is intentionally NOT duplicated here.
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*/
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attributes: Record<string, string | number>
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/**
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* The complete payload: a deep copy of the session event's `data` for
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* ledger records (JSON-serializable by `Session.append`'s own
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* validation), or the op payload for ops records. Never mutated after
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* handoff.
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*/
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body: unknown
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}
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```
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Only the first `assistant/chunk` of each `(turn, step)` ships — the stream-started signal; the rest drop at capture, so `seq` gaps are routine on the wire and never a loss signal. Every other [session event](session.md) type, including plugin-merged ones the seam never heard of, passes through whole. Delivery is best-effort: the cursor marks handed-off, not delivered, records can be lost (crash, reload window) and duplicated (cursor-less re-adoption, SDK retries), so receivers dedupe ledger records on `(session.id, event.seq)`; ops records deliberately omit that identity — they are signals to alert on, not entries to sum, and tolerate duplicates instead.
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## The sharing disclosure
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The seam's acknowledgement contract (owned by the [Service Definition README's sharing-disclosure section](../../packages/session/session-telemetry/README.md#the-sharing-disclosure)): every backend discloses its deployment-selected sharing policy through the required abstract `sharing` member on `ctx.telemetry`, and consumers render "not configured" only when no telemetry service is mounted. The disclosure states the current policy, never delivery or retention — handoff is the non-blocking enqueue, and batching, retry, and loss policy stay the reporting SDK's.
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```ts type-equiv
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/**
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* Deployment-selected session-sharing policy disclosed by a mounted
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* {@link Telemetry} backend to human-facing acknowledgement surfaces (the
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* `/feedback` command's confirmation text). The seam owns the vocabulary so
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* any backend can disclose a policy without depending on the OTel package;
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* the values mirror the OTel backend's serialized `TelemetryMode` choices.
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*/
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type TelemetrySharingStatus = 'full' | 'feedback-only' | 'disabled'
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```
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## The backend contract
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```ts type-equiv
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/**
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* The minimum backend contract the coordinator requires. {@link Telemetry} is
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* its service-registered form; tests compose the coordinator with a bare
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* implementation of this interface.
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*/
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interface TelemetryBackend {
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/**
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* Hand one record to the backend's pipeline. MUST be a non-blocking
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* enqueue — the coordinator calls this synchronously from the
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* `session/event` hot path or an explicit canonical-log capture, so anything
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* slower than a queue push would tax the agent loop or feedback handling.
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* Errors thrown here are contained by the coordinator and logged; they
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* never reach the loop.
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* @param record - the logical record to report; owned by the backend after the call.
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*/
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emit(record: TelemetryRecord): void
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/**
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* Optional hint that a turn ended. A backend may forward it to its SDK's
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* flush so records are exported after each turn. Called
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* fire-and-forget; implementations must not block and must not throw
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* meaningfully (the coordinator contains exceptions). Most backends should
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* leave this unimplemented and let their SDK's own batching cadence govern
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* export timing: a backend that does implement it owns the interaction
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* between its concurrent flushes and {@link shutdown}'s drain (the OTel
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* backend leaves it unimplemented for exactly that hazard — see the
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* revival Agent Note).
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*/
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flush?(): void
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/**
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* Forward the fiber's disposal to the SDK: flush whatever is queued and
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* reach quiescence, per the SDK's own shutdown contract. Everything
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* emitted before this call must still be delivered — including records
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* enqueued while a {@link flush} hint is in flight, so a backend whose SDK
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* guards against concurrent flushes orders behind the outstanding one (the
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* coordinator emits its dispose-time `shutdown` markers immediately before
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* calling this). Awaited by the coordinator's dispose; a rejection is
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* logged as a warning and never fails application teardown.
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* The coordinator captures dispose-time shutdown markers immediately before
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* this call for live capture; on-demand capture creates no ops records.
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* @returns resolves when the backend's pipeline has quiesced.
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*/
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shutdown(): Promise<void>
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}
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```
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`Telemetry` (`ctx.telemetry`, [signatures](#ctxtelemetry--telemetry-abstract-seam)) is the contract's loadable form — one implementation per context, duplicate load throws — and a backend composes the seam's `TelemetryCoordinator` in its constructor to install the capture side.
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## The redact waterfall: `telemetry/record`
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Every record passes the `telemetry/record` [waterfall](../cordis-primer.md#cordis-waterfall-semantics) between projection and `emit()` ([event entry](#telemetryrecord--waterfall)). The seam ships NO rules of its own: with no listener mounted, records reach the backend exactly as captured, so exported data is precisely as clean as the rules a deployment mounts. Listeners stack by transforming `next()`'s return value; returning without `next()` replaces everything beneath; a throwing listener withholds that one record fail-closed inside the coordinator's containment. Redaction applies to the exported copy only — the canonical session log is never rewritten.
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<!-- BEGIN GENERATED cordis-surface (gen-cordis-catalog.ts) — do not edit between markers -->
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<a id="cordis-surface"></a>
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## Cordis API
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Generated from source by `scripts/gen-cordis-catalog.ts` (verified fresh by `pnpm run verify-cordis-catalog` in doc-sync; regenerate with `pnpm run gen-cordis-catalog`) — this section is byte-identical in both language sides of the page. Signature blocks use a `ts cordis-catalog` fence and keep the original source JSDoc; dispatch modes are defined in the [primer](../cordis-primer.md#dispatch-modes), and the framework-inherited `ctx` API lives in [cordis-api/inherited.md](../cordis-api/inherited.md).
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<a id="ctxtelemetry--telemetry-abstract-seam"></a>
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### `ctx.telemetry` — `Telemetry` (abstract seam)
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Loadable form of the backend contract: one implementation per context — the cordis `Service` registration under the `telemetry` key throws on a duplicate, cordis' standard behavior. A backend composes a TelemetryCoordinator in its constructor to install the capture side.
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```ts cordis-catalog
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/**
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* See {@link TelemetryBackend.emit} — that declaration is the contract's one home.
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* @param record - the logical record to report; owned by the backend after the call.
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*/
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abstract emit(record: TelemetryRecord): void
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/** See {@link TelemetryBackend.flush}. */
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flush?(): void
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/**
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* See {@link TelemetryBackend.shutdown}.
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* @returns resolves when the backend's pipeline has quiesced.
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*/
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abstract shutdown(): Promise<void>
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```
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Source: [`packages/session/session-telemetry/src/index.ts:148`](../../packages/session/session-telemetry/src/index.ts)
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<a id="telemetry-events"></a>
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### `telemetry/*` events
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<a id="telemetryrecord--waterfall"></a>
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#### `telemetry/record` — waterfall
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Transform one outbound record before it reaches the backend. This waterfall is the Service Definition's redaction extension point. It ships NO rules of its own: the innermost `next()` passes the record through unchanged, and with no listener mounted records reach the backend as captured, so exported data is exactly as clean as the rules a deployment mounts. Listeners stack by transforming `next()`'s return value; returning without `next()` replaces everything beneath. Dispatched synchronously on the capture hot path inside the coordinator's containment: a throwing listener withholds that one record (fail-closed) and never reaches the agent loop. Live capture dispatches at append time; on-demand capture dispatches while reading the canonical log. Redaction applies to the exported copy only; the canonical session log is never rewritten.
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```ts cordis-catalog
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/**
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* Transform one outbound record before it reaches the backend. This
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* waterfall is the Service Definition's redaction extension point. It ships NO rules
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* of its own: the
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* innermost `next()` passes the record through unchanged, and with no
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* listener mounted records reach the backend as captured, so exported
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* data is exactly as clean as the rules a deployment mounts. Listeners
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* stack by transforming `next()`'s return value; returning without
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* `next()` replaces everything beneath. Dispatched synchronously on the
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* capture hot path inside the coordinator's containment: a throwing
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* listener withholds that one record (fail-closed) and never reaches the
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* agent loop. Live capture dispatches at append time; on-demand capture
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* dispatches while reading the canonical log. Redaction applies to the
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* exported copy only; the canonical session log is never rewritten.
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* @param record - the candidate record, already the coordinator's own deep
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* copy; listeners return a (possibly new) record and must not mutate it.
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* @mode waterfall
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*/
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'telemetry/record'(record: TelemetryRecord, next: () => TelemetryRecord): TelemetryRecord
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```
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Source: [`packages/session/session-telemetry/src/index.ts:43`](../../packages/session/session-telemetry/src/index.ts)
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<!-- END GENERATED cordis-surface -->
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