docs(cordis): clarify serial bail semantics

AGENTS.md

@@ -250,7 +250,7 @@ In the **core** packages (`packages/llm/llm`, `packages/core/tools`, `packages/c
 
 Verbose documentation is fine **as long as docs and code stay strictly in sync**. Out-of-sync docs are worse than no docs. **When you change code, update its docs in the SAME change** — grep the package README and the module/JSDoc comments for the old behavior (config keys, defaults, error codes, wire field names, event names) and fix every hit. CI runs `pnpm run doc-sync` (`doc-typecheck` + `verify-cordis-catalog` + `verify-md-wrap` + `verify-md-links` + `verify-doc-refs` + `verify-package-paths` + `verify-rfc-classification` + `verify-type-equiv`), which typechecks every fenced `ts` block in `README.md`, `docs/**/*.md`, and `packages/*/*.md`, regenerates the cordis events/services catalog from source and fails if the committed copy is stale, asserts no hard-wrapped prose paragraphs, checks that every relative Markdown cross-link resolves, checks that every `docs/*.md` path cited in a source comment resolves, checks that every `packages/<path>` reference naming a real package resolves, checks that every RFC is filed under a valid class folder and listed in its index, and checks that every ` ```ts type-equiv ` doc block still matches its source type — across those files plus `AGENTS.md` / `packages/AGENTS.md` — but that scope does NOT catch prose drift in `AGENTS.md` / `packages/AGENTS.md` / `packages/README.md` (config keys, defaults, error codes), so keeping those in sync remains on the author. Every module has a module-level doc comment explaining its role. Every exported class, interface, type, function, and non-obvious method has a JSDoc that explains semantics (not just the name) — contracts (what events fire when), disposal behavior, error behavior, and extension intent. Internal helpers get docs only where non-obvious. Prefer one-liners when one line suffices.
 
-**Tag every new event with `@mode`.** The cordis events/services catalog ([docs/cordis-catalog/events-and-services.md](docs/cordis-catalog/events-and-services.md)) is GENERATED from source by `scripts/gen-cordis-catalog.ts` — never hand-edit it; run `pnpm run gen-cordis-catalog` and commit the result. When you add an event to an `interface Events` block, its JSDoc MUST carry a `@mode emit|waterfall|parallel|serial` tag (the generator hard-errors without it): use `waterfall` when the signature ends with a `next: () => …` parameter (the listener transforms or vetoes via `next()`), `parallel` when the loop awaits a fan-out with no veto (e.g. an awaited `Promise<void> | void` checkpoint like `session/flush`), `serial` when the loop awaits listeners in registration order with no veto (e.g. an ordered surface-mutation checkpoint like `agent/pre-step`), and `emit` for plain fire-and-forget notifications. The generator also cross-checks the tag against the signature where the shape is conclusive (a trailing `next` ⇒ waterfall) and hard-errors on a contradiction. Write the rest of the event's JSDoc to stand alone — it is the catalog entry's prose.
+**Tag every new event with `@mode`.** The cordis events/services catalog ([docs/cordis-catalog/events-and-services.md](docs/cordis-catalog/events-and-services.md)) is GENERATED from source by `scripts/gen-cordis-catalog.ts` — never hand-edit it; run `pnpm run gen-cordis-catalog` and commit the result. When you add an event to an `interface Events` block, its JSDoc MUST carry a `@mode emit|waterfall|parallel|serial` tag (the generator hard-errors without it): use `waterfall` when the signature ends with a `next: () => …` parameter (the listener transforms or vetoes via `next()`), `parallel` when the loop awaits a fan-out and must run every listener (e.g. an awaited `Promise<void> | void` checkpoint like `session/flush`), `serial` when the loop awaits listeners in registration order and should isolate side effects (e.g. an ordered surface-mutation checkpoint like `agent/pre-step`; Cordis stops early if a listener returns a bail value, so `void` serial listeners must not return a semantic veto), and `emit` for plain fire-and-forget notifications. The generator also cross-checks the tag against the signature where the shape is conclusive (a trailing `next` ⇒ waterfall) and hard-errors on a contradiction. Write the rest of the event's JSDoc to stand alone — it is the catalog entry's prose.
 
 **The core-data-structures catalog is a maintained surface, not a write-once artifact.** [docs/core-data-structures/](docs/core-data-structures/core.md) catalogs the spine vocabulary (core.md) and the per-seam types (sub-pages). When a change adds, removes, or reshapes a type the catalog documents — a new `…Map` variant, a new content-block or session-event type, a field on `GenerateOptions`/`Agent`/`ToolDefinition`/a bash type, or a whole new core/seam type — update the catalog in the SAME change: edit the prose, and for a pasted ` ```ts type-equiv ` block, re-copy it verbatim and keep `scripts/type-equiv.manifest.json` 1:1 with the blocks. The `verify-type-equiv` gate catches a *drifted paste* of an already-documented type, but it canNOT tell you a brand-new core type was never documented — that judgment is on the author and the reviewer. The definition of "core" (the spine-vs-seam line) is in [core.md § What counts as "core"](docs/core-data-structures/core.md#what-counts-as-core); a genuinely spine-level new type belongs in core.md, a new capability's vocabulary on a sub-page. See [development.md](docs/development.md#documenting-types-verbatim-ts-type-equiv) for the `ts type-equiv` mechanics.
 

docs/cordis-catalog/events-and-services.md

@@ -11,7 +11,7 @@ The **harness tier** below (the `@deepseek-ai/dsh-*` packages) is the vocabulary
 
 ## Events
 
-Dispatch modes: **emit** (fire-and-forget), **waterfall** (each listener gets `next()` and may transform or veto — see [waterfall semantics](../architecture.md#cordis-waterfall-semantics-important)), **parallel** (awaited fan-out, no veto), **serial** (awaited, in registration order, no veto).
+Dispatch modes: **emit** (fire-and-forget), **waterfall** (each listener gets `next()` and may transform or veto — see [waterfall semantics](../architecture.md#cordis-waterfall-semantics-important)), **parallel** (awaited fan-out; all listeners run), **serial** (awaited in registration order until one returns a bail value — anything other than `null`, `false`, or `undefined`).
 
 ### `agent/*`
 
@@ -49,13 +49,13 @@ A step or turn errored. The loop reports a failure here (plus the logger) even w
 
 Types: [Agent](../core-data-structures/core.md)
 
-Source: [`packages/core/agent/src/types.ts:248`](../../packages/core/agent/src/types.ts)
+Source: [`packages/core/agent/src/types.ts:249`](../../packages/core/agent/src/types.ts)
 
 #### `agent/pre-step` — serial
 
 Awaited pre-step surface-mutation checkpoint, fired once per step AFTER `turn/start` (and after the prior step closed) but BEFORE this step's `step/start` — so anything a listener appends lands OUTSIDE the step, between `turn/start`/`step/end` and the upcoming `step/start`. `step` is the number of the step about to start. The loop awaits `ctx.serial('agent/pre-step', …)` after assembling the system prompt, then opens the step and derives the request history ONCE from whatever the surface now holds. This is where compaction belongs: it mutates the session surface in place (shadowing an older range with a summary node) with its log-only `compact/*` records cleanly outside any step, and the single subsequent derive reflects the mutation — so there is no double-derive and no listener can see (or be expected to act on) an assembled `messages` array that does not exist yet.
 
-Serial (awaited, in registration order, no veto), not a waterfall: a listener mutates the surface as a side effect; there is nothing to transform or veto, but the loop must wait for the mutation to complete before opening the step and deriving, and serial isolates listeners from each other (one finishes its surface append before the next runs). `fullSystemPrompt` is the assembled prompt a listener needs to measure pressure (the system prompt counts toward the budget). `signal` cancels any in-flight work a listener starts (e.g. a summarization model call).
+Serial (awaited in registration order), not a waterfall: a listener mutates the surface as a side effect; there is nothing to transform, but the loop must wait for the mutation to complete before opening the step and deriving. Cordis `serial` bails early if a listener returns a bail value; this event is typed and documented as `void`, so listeners must not return a semantic veto value. `fullSystemPrompt` is the assembled prompt a listener needs to measure pressure (the system prompt counts toward the budget). `signal` cancels any in-flight work a listener starts (e.g. a summarization model call).
 
 ```ts cordis-catalog
 'agent/pre-step'(agent: Agent, turn: number, step: number, fullSystemPrompt: string, signal: AbortSignal): Promise<void> | void
@@ -63,7 +63,7 @@ Serial (awaited, in registration order, no veto), not a waterfall: a listener mu
 
 Types: [Agent](../core-data-structures/core.md)
 
-Source: [`packages/core/agent/src/types.ts:208`](../../packages/core/agent/src/types.ts)
+Source: [`packages/core/agent/src/types.ts:209`](../../packages/core/agent/src/types.ts)
 
 #### `agent/queued` — emit
 
@@ -87,7 +87,7 @@ Waterfall: mutate the fully-assembled GenerateOptions before the model call (hoo
 
 Types: [Agent](../core-data-structures/core.md) · [GenerateOptions](../core-data-structures/core.md)
 
-Source: [`packages/core/agent/src/types.ts:217`](../../packages/core/agent/src/types.ts)
+Source: [`packages/core/agent/src/types.ts:218`](../../packages/core/agent/src/types.ts)
 
 #### `agent/status` — emit
 
@@ -111,7 +111,7 @@ Steering content was injected into a running turn.
 
 Types: [Agent](../core-data-structures/core.md) · [ContentBlock](../core-data-structures/core.md) · [MessageSource](../core-data-structures/core.md)
 
-Source: [`packages/core/agent/src/types.ts:242`](../../packages/core/agent/src/types.ts)
+Source: [`packages/core/agent/src/types.ts:243`](../../packages/core/agent/src/types.ts)
 
 #### `agent/step-end` — emit
 
@@ -135,7 +135,7 @@ Waterfall: post-process the assembled assistant Message before tool dispatch (va
 
 Types: [Agent](../core-data-structures/core.md) · [Message](../core-data-structures/core.md)
 
-Source: [`packages/core/agent/src/types.ts:223`](../../packages/core/agent/src/types.ts)
+Source: [`packages/core/agent/src/types.ts:224`](../../packages/core/agent/src/types.ts)
 
 #### `agent/step-start` — emit
 
@@ -159,7 +159,7 @@ A raw StreamChunk arrived from the model (token-level UI/log feed).
 
 Types: [Agent](../core-data-structures/core.md) · [StreamChunk](../core-data-structures/llm-streaming.md)
 
-Source: [`packages/core/agent/src/types.ts:237`](../../packages/core/agent/src/types.ts)
+Source: [`packages/core/agent/src/types.ts:238`](../../packages/core/agent/src/types.ts)
 
 #### `agent/turn-continuation` — waterfall
 
@@ -171,7 +171,7 @@ Waterfall: override the turn-continuation decision. The default (computed by the
 
 Types: [Agent](../core-data-structures/core.md)
 
-Source: [`packages/core/agent/src/types.ts:230`](../../packages/core/agent/src/types.ts)
+Source: [`packages/core/agent/src/types.ts:231`](../../packages/core/agent/src/types.ts)
 
 #### `agent/turn-end` — emit
 
@@ -511,7 +511,7 @@ The framework surface every plugin inherits, beyond the harness vocabulary above
 ### Inherited `ctx` members
 
 - `ctx.on / ctx.once` — Register an event listener (disposable). ([`vendor/cordis/src/events.ts:29`](../../vendor/cordis/src/events.ts))
-- `ctx.emit / ctx.parallel / ctx.serial / ctx.bail / ctx.waterfall` — Dispatch an event (sync / awaited / first-non-nullish / veto-chain). ([`vendor/cordis/src/events.ts:29`](../../vendor/cordis/src/events.ts))
+- `ctx.emit / ctx.parallel / ctx.serial / ctx.bail / ctx.waterfall` — Dispatch an event (sync / awaited / first-bail / veto-chain). ([`vendor/cordis/src/events.ts:29`](../../vendor/cordis/src/events.ts))
 - `ctx.plugin / ctx.inject` — Load a plugin / declare required services. ([`vendor/cordis/src/registry.ts:144`](../../vendor/cordis/src/registry.ts))
 - `ctx.effect` — Register a disposable side effect tied to the fiber. ([`vendor/cordis/src/fiber.ts:9`](../../vendor/cordis/src/fiber.ts))
 - `ctx.get / ctx.set / ctx.provide / ctx.accessor / ctx.mixin` — Low-level service-store access and binding. ([`vendor/cordis/src/reflect.ts:7`](../../vendor/cordis/src/reflect.ts))

docs/rfc/implemented/feature/2026-06-18-compaction-capability-seam.md

@@ -46,7 +46,7 @@ messages = session.deriveMessages()   ⟵ single derive, reflects the compaction
 request  = waterfall agent/request    ⟵ pure request transform (hooks, model switch)
 ```
 
-This makes the layering correct *by construction*: compaction mutates the surface, the loop derives **once** from the result (no double-derive), and at `pre-step` the assembled `messages` do not yet exist — so a listener structurally *cannot* see or be expected to act on downstream-injected context. `agent/request` reverts to a pure request transformer. Firing the seam **before** `step/start` (not inside the open step) is load-bearing for crash-safety: compaction's log-only `compact/*` records and its replacement node land *outside* any step, so the honest log structure a crash leaves (a dangling `compact/start` sitting before the synthetic `turn/end` that turn-repair appends) holds without a half-open step to reconcile. The seam is `serial` (awaited, in registration order, no veto), not `parallel`: a listener mutates the surface as a side effect — there is nothing to transform or return — and serial isolates listeners from each other so two surface-mutating listeners can never interleave their `session.append`s.
+This makes the layering correct *by construction*: compaction mutates the surface, the loop derives **once** from the result (no double-derive), and at `pre-step` the assembled `messages` do not yet exist — so a listener structurally *cannot* see or be expected to act on downstream-injected context. `agent/request` reverts to a pure request transformer. Firing the seam **before** `step/start` (not inside the open step) is load-bearing for crash-safety: compaction's log-only `compact/*` records and its replacement node land *outside* any step, so the honest log structure a crash leaves (a dangling `compact/start` sitting before the synthetic `turn/end` that turn-repair appends) holds without a half-open step to reconcile. The seam is `serial` (awaited, in registration order), not `parallel`: a listener mutates the surface as a side effect — there is nothing to transform or return — and serial isolates listeners from each other so two surface-mutating listeners can never interleave their `session.append`s. Cordis `serial` does bail early if a listener returns a bail value, so `agent/pre-step` listeners are typed/documented to return `void` and must not use that bail channel as a semantic veto surface.
 
 This **amends** the original RFC's claim of "NO changes to `dsh-agent-loop`; compaction is a pure plugin." That claim was load-bearing for a wrong design — reusing `agent/request` was the mistake. Per the pre-release "foundation over blast radius" stance, adding the correct seam (one event declaration in `dsh-agent`, one awaited emit in the loop) beats preserving a no-change boast that locked in the double-derive.
 

packages/compact/compact-basic/README.md

@@ -14,7 +14,7 @@ The abstract contract states only WHAT compaction does; this backend owns every
 - **Summarization** — `summarize()`: a `GenerateOptions` request assembled via `BlockAssembler` with a fixed system prompt that asks for a structured checkpoint (Primary Request and Intent · Key Technical Concepts · Files and Code · Errors and Fixes · Pending Tasks · Current Work · Next Step · Critical Context), every section mandatory, exact paths/commands/identifiers preserved. The request runs through the `agent/request` waterfall before `ctx.llm.stream()`, so router agents that choose the concrete model there also route compaction summaries. `maxTokens` is the provider-side generation cap; only text blocks from the model's reply are kept before the checkpoint is stored (reasoning is dropped so private chain-of-thought never leaks into the durable summary, and a stray `tool-call` is dropped so the synthesized `user/message` summary cannot land an orphaned call with no matching `tool-result`). The compacted region is flattened to a plain-text transcript first: text and reasoning contribute their text, and every non-text block (image, tool-call, tool-result, plugin-added types) contributes a type-tagged placeholder (`[image]`, `[tool-call: name(args)]`, …) so the summarizer is told what existed rather than silently dropping it.
 - **Checkpoint framing** — the raw summary is not landed directly. `compactRegion()` wraps it in a checkpoint preamble (so a resuming model reads it as a checkpoint, not a fresh user request, and builds on the captured context rather than restating it) plus `<compacted-summary>…</compacted-summary>` tags. Because region compaction can be invoked manually, a surface may hold several checkpoints, so the framing does not claim everything after it is recent or verbatim. The tags make a prior checkpoint detectable in the transcript on the next compaction cycle: the summarization prompt then instructs the model to merge it in place (preserve still-true facts, drop stale ones) rather than re-summarize it verbatim — a cheap incremental merge that needs no extra log/event machinery. The unframed summary stays on the `compact/summary` provenance event.
 - **Surface mutation** — `compactRegion()` appends the `compact/start` → `compact/summary` → `compact/end` log records and the single `user/message` replace node carrying the framed summary (see the interface README).
-- **Auto-compaction** — an `agent/pre-step` listener delegates to `compactIfNeeded()` before every step (not just a turn's first — a tool-heavy turn grows the surface mid-turn, so a runaway turn still compacts, and per-step firing is the only moment to rescue it before overflow). `agent/pre-step` is a serial (awaited, in-order, no-veto) surface-mutation checkpoint that fires after `turn/start` and BEFORE the step opens (`step/start`) and its request history is derived, so compaction mutates the surface — with its log-only `compact/*` records landing cleanly outside any step — and the loop derives once from the result: no double-derive, and the listener cannot see (or need to rewrite) an already-assembled `messages` array. The listener owns no threshold logic of its own (the single token-pressure check lives in `compactIfNeeded()`).
+- **Auto-compaction** — an `agent/pre-step` listener delegates to `compactIfNeeded()` before every step (not just a turn's first — a tool-heavy turn grows the surface mid-turn, so a runaway turn still compacts, and per-step firing is the only moment to rescue it before overflow). `agent/pre-step` is a serial (awaited, in-order) surface-mutation checkpoint that fires after `turn/start` and BEFORE the step opens (`step/start`) and its request history is derived, so compaction mutates the surface — with its log-only `compact/*` records landing cleanly outside any step — and the loop derives once from the result: no double-derive, and the listener cannot see (or need to rewrite) an already-assembled `messages` array. The listener owns no threshold logic of its own (the single token-pressure check lives in `compactIfNeeded()`); because Cordis `serial` bails early on non-void return values, the listener returns `void` and does not use the dispatcher's bail channel as a veto surface.
 - **Failure handling** — the `compact/start … compact/end` bracket is a log-recorded lock: it makes a crash mid-summarization a detectable orphan (a `compact/start` with no `compact/end`), records provenance, and prevents a concurrent compaction. Two failure paths: a **crash** (the loop dies mid-summarization) leaves a dangling `compact/start` that is inert — `compact/*` events are log-only, the surface replacement never landed, so the full history derives fine and generic turn-repair closes the turn; a **recoverable** failure (summarization throws but the loop survives) appends `compact/end` with its `error` field set, leaving the surface untouched so the call proceeds with full history. Core session repair stays compaction-agnostic by design — it never learns about `compact/*`.
 
 `estimateContentTokens()` and `summarize()` are overridable hooks: a tokenizer-based or template-based backend can subclass `BasicCompactService` and override just those, reusing the retention walk and surface plumbing.

packages/core/agent/src/types.ts

@@ -195,14 +195,15 @@ declare module 'cordis' {
      * no listener can see (or be expected to act on) an assembled `messages`
      * array that does not exist yet.
      *
-     * Serial (awaited, in registration order, no veto), not a waterfall: a
-     * listener mutates the surface as a side effect; there is nothing to
-     * transform or veto, but the loop must wait for the mutation to complete
-     * before opening the step and deriving, and serial isolates listeners from
-     * each other (one finishes its surface append before the next runs).
-     * `fullSystemPrompt` is the assembled prompt a listener needs to measure
-     * pressure (the system prompt counts toward the budget). `signal` cancels any
-     * in-flight work a listener starts (e.g. a summarization model call).
+     * Serial (awaited in registration order), not a waterfall: a listener
+     * mutates the surface as a side effect; there is nothing to transform, but
+     * the loop must wait for the mutation to complete before opening the step
+     * and deriving. Cordis `serial` bails early if a listener returns a bail
+     * value; this event is typed and documented as `void`, so listeners must not
+     * return a semantic veto value. `fullSystemPrompt` is the assembled prompt a
+     * listener needs to measure pressure (the system prompt counts toward the
+     * budget). `signal` cancels any in-flight work a listener starts (e.g. a
+     * summarization model call).
      * @mode serial
      */
     'agent/pre-step'(agent: Agent, turn: number, step: number, fullSystemPrompt: string, signal: AbortSignal): Promise<void> | void

scripts/gen-cordis-catalog.ts

@@ -331,7 +331,7 @@ const INHERITED_EVENTS: InheritedEntry[] = [
 
 const INHERITED_SERVICES: InheritedEntry[] = [
   { name: 'ctx.on / ctx.once', summary: 'Register an event listener (disposable).', source: 'vendor/cordis/src/events.ts:29' },
-  { name: 'ctx.emit / ctx.parallel / ctx.serial / ctx.bail / ctx.waterfall', summary: 'Dispatch an event (sync / awaited / first-non-nullish / veto-chain).', source: 'vendor/cordis/src/events.ts:29' },
+  { name: 'ctx.emit / ctx.parallel / ctx.serial / ctx.bail / ctx.waterfall', summary: 'Dispatch an event (sync / awaited / first-bail / veto-chain).', source: 'vendor/cordis/src/events.ts:29' },
   { name: 'ctx.plugin / ctx.inject', summary: 'Load a plugin / declare required services.', source: 'vendor/cordis/src/registry.ts:144' },
   { name: 'ctx.effect', summary: 'Register a disposable side effect tied to the fiber.', source: 'vendor/cordis/src/fiber.ts:9' },
   { name: 'ctx.get / ctx.set / ctx.provide / ctx.accessor / ctx.mixin', summary: 'Low-level service-store access and binding.', source: 'vendor/cordis/src/reflect.ts:7' },
@@ -394,7 +394,7 @@ function render(events: EventEntry[], services: ServiceEntry[]): string {
     '',
     '## Events',
     '',
-    'Dispatch modes: **emit** (fire-and-forget), **waterfall** (each listener gets `next()` and may transform or veto — see [waterfall semantics](../architecture.md#cordis-waterfall-semantics-important)), **parallel** (awaited fan-out, no veto), **serial** (awaited, in registration order, no veto).',
+    'Dispatch modes: **emit** (fire-and-forget), **waterfall** (each listener gets `next()` and may transform or veto — see [waterfall semantics](../architecture.md#cordis-waterfall-semantics-important)), **parallel** (awaited fan-out; all listeners run), **serial** (awaited in registration order until one returns a bail value — anything other than `null`, `false`, or `undefined`).',
     '',
   ]
   const scopes = [...new Set(events.map(e => e.scope))].sort()