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refactor(agent): rename agent/request-messages to agent/request-advice

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tianyicui's review: the seam name did not say what the event or its
types do. 'advice' reads both ways — advisory content for the model,
and AOP before/after advice woven around a join point (here the
derived history) without modifying it — so RequestAdvice.before/after
are self-describing. Types follow: RequestAdvice / RequestAdviceContext;
the logged EpochHeader fields keep their positional names
(messagePrefix/messageSuffix).

Also sharpens the core.md wording the review flagged as ambiguous:
before-advice sits in front of the ENTIRE derived history, directly
after the system slot (the conventional home for session-stable openers
— an AGENTS.md digest, a skills catalog), after-advice follows the
history's last message. Catalogs and doc graphs regenerated.
This commit is contained in:
Yichen Jiang
2026-07-08 10:05:34 +08:00
parent 731ae2443c
commit e97fffeab7
15 files changed
+117 -108
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docs/architecture.md
+2 -2
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@@ -72,7 +72,7 @@ forever:
agent/pre-step
'step/start'
snapshot the derived messages (the reconstruction boundary)
agent/request (config only) -> agent/request-messages -> log request/header -> llm/stream (frozen)
agent/request (config only) -> agent/request-advice -> log request/header -> llm/stream (frozen)
'assistant/chunk'
agent/step-result
'assistant/message'
@@ -141,7 +141,7 @@ New behavior should attach to a documented seam; changing the shipped loop requi
| Add command execution | implement and register a `ctx.bash` backend |
| Add filesystem access or policy | implement a `ctx.fs` provider or listen on `fs/*` policy events |
| Intercept prompts, requests, tool use, or continuation | listen on the relevant `agent/*` or `tools/*` waterfall |
| Add per-request context that must not become history | contribute request-only messages on `agent/request-messages`; logged on the request header |
| Add per-request context that must not become history | contribute request-only messages on `agent/request-advice`; logged on the request header |
| Add UI or editor integration | drive `ctx.agents` and render from `session/event` |
| Add durable session state | add a `SessionEventMap` member and render/replay from the log |
| Fork a live session | use `ctx.sessions.fork(source, boundary?, childSessionId?)` |
docs/cordis-catalog/events.md
+17 -17
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@@ -23,7 +23,7 @@ An agent was registered in the AgentRegistry and is ready to receive messages.
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:308`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:313`](../../packages/core/agent/src/types.ts)
### `agent/disposed` — emit
@@ -35,7 +35,7 @@ An agent was disposed and removed from the registry; its fiber and any in-flight
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:315`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:320`](../../packages/core/agent/src/types.ts)
### `agent/error` — emit
@@ -47,7 +47,7 @@ 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:506`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:512`](../../packages/core/agent/src/types.ts)
### `agent/pre-step` — serial
@@ -61,7 +61,7 @@ Serial (awaited in registration order), not a waterfall: a listener mutates the
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:393`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:398`](../../packages/core/agent/src/types.ts)
### `agent/prompt-submit` — waterfall
@@ -73,7 +73,7 @@ Waterfall: decide what happens to ONE drained queued message before it becomes a
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:406`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:411`](../../packages/core/agent/src/types.ts)
### `agent/queued` — emit
@@ -85,11 +85,11 @@ A message entered the agent's inbox (queued or steering). `source` is the resolv
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:333`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:338`](../../packages/core/agent/src/types.ts)
### `agent/request` — waterfall
Waterfall: shape the step's call configuration — model switching, sampling overrides — by returning a replacement LlmCallConfig (the frozen seed is the config the loop would otherwise use). Config is ALL a listener shapes here: every request is a pure function of the session log (the reconstructability RFC), so model-visible content flows through the log channels — `inject()`, steering, prompt-submit `additionalContext`, prompt sections via `system-prompt/assemble`, or header-logged request-only messages via agent/request-messages — never through request mutation, and the loop records whatever config the request actually uses as a `request/header*` event before dispatch. The step's messages are already snapshotted when this fires (the `step/start` boundary): an `inject()` from a listener here lands in the log but joins the NEXT request. For surface mutation that must precede the snapshot (compaction), use agent/pre-step. Call `next()` to delegate, or return an LlmCallConfig without it to short-circuit.
Waterfall: shape the step's call configuration — model switching, sampling overrides — by returning a replacement LlmCallConfig (the frozen seed is the config the loop would otherwise use). Config is ALL a listener shapes here: every request is a pure function of the session log (the reconstructability RFC), so model-visible content flows through the log channels — `inject()`, steering, prompt-submit `additionalContext`, prompt sections via `system-prompt/assemble`, or header-logged request-only messages via agent/request-advice — never through request mutation, and the loop records whatever config the request actually uses as a `request/header*` event before dispatch. The step's messages are already snapshotted when this fires (the `step/start` boundary): an `inject()` from a listener here lands in the log but joins the NEXT request. For surface mutation that must precede the snapshot (compaction), use agent/pre-step. Call `next()` to delegate, or return an LlmCallConfig without it to short-circuit.
```ts cordis-catalog
'agent/request'(agent: Agent, turn: number, step: number, config: LlmCallConfig, next: () => Promise<LlmCallConfig>): Promise<LlmCallConfig>
@@ -97,23 +97,23 @@ Waterfall: shape the step's call configuration — model switching, sampling ove
Types: [Agent](../core-data-structures/core.md) · [LlmCallConfig](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:430`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:435`](../../packages/core/agent/src/types.ts)
### `agent/request-messages` — waterfall
### `agent/request-advice` — waterfall
Waterfall: contribute request-ONLY messages around the derived history — a RequestMessages whose `before` messages precede the boundary snapshot in `GenerateOptions.messages` and whose `after` messages follow it. Fires once per step, inside the open step, after the agent/request config waterfall and before the loop logs the request header. This is the seam for per-request advisory context the model must see NOW but that must NOT become durable history (a skills catalog, an environment reminder): contributions are recorded on the request's `request/header*` event (`EpochHeader.messagePrefix` / `messageSuffix`) — never as session messages — so `Session.deriveMessages()` stays untouched and the request remains reconstructable from the log.
Waterfall: weave request-ONLY advice around the derived history — a RequestAdvice whose `before` messages sit in front of the ENTIRE boundary snapshot in `GenerateOptions.messages` and whose `after` messages follow its last message. Fires once per step, inside the open step, after the agent/request config waterfall and before the loop logs the request header. This is the seam for per-request advisory context the model must see NOW but that must NOT become durable history (a skills catalog, an environment reminder): contributions are recorded on the request's `request/header*` event (`EpochHeader.messagePrefix` / `messageSuffix`) — never as session messages — so `Session.deriveMessages()` stays untouched and the request remains reconstructable from the log.
The seed is frozen and empty; a contributing listener returns a NEW RequestMessages extending `await next()` (spread its arrays — never mutate them), so contributions compose across plugins in registration order. The boundary snapshot is already taken when this fires: a `session.append`/`inject()` from a listener here lands in the log but joins the NEXT request — contribute through the returned value, not the session. Call `next()` to delegate, or return a RequestMessages without it to short-circuit.
The seed is frozen and empty; a contributing listener returns a NEW RequestAdvice extending `await next()` (spread its arrays — never mutate them), so contributions compose across plugins in registration order. The boundary snapshot is already taken when this fires: a `session.append`/`inject()` from a listener here lands in the log but joins the NEXT request — contribute through the returned value, not the session. Call `next()` to delegate, or return a RequestAdvice without it to short-circuit.
Pick the channel by change frequency (the cost model): a contribution rides the request's uncached tail, re-tokenized at full price on EVERY request it appears in — cheap only while small. Session-FROZEN content belongs in `before`, where it extends the cacheable prefix at zero marginal cost (but changing it mid-session invalidates the provider cache for the entire history after it). A LOW-FREQUENCY change notice belongs in durable history via `agent.inject()` — appended once, prefix-cached thereafter. Reserve `after` for small, frequently refreshed state snapshots, where a durable chain of stale copies would bloat the log and mislead the model.
```ts cordis-catalog
'agent/request-messages'(agent: Agent, turn: number, step: number, messages: RequestMessages, context: RequestMessagesContext, next: () => Promise<RequestMessages>): Promise<RequestMessages>
'agent/request-advice'(agent: Agent, turn: number, step: number, advice: RequestAdvice, context: RequestAdviceContext, next: () => Promise<RequestAdvice>): Promise<RequestAdvice>
```
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:471`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:477`](../../packages/core/agent/src/types.ts)
### `agent/session-start` — emit
@@ -125,7 +125,7 @@ The agent's session lifecycle began, fired once before its first turn. `source`
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:348`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:353`](../../packages/core/agent/src/types.ts)
### `agent/status` — emit
@@ -137,7 +137,7 @@ Agent status changed (`idle` ⇄ `running`, or → `disposed`). Drive lifecycle
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:324`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:329`](../../packages/core/agent/src/types.ts)
### `agent/step-result` — waterfall
@@ -149,7 +149,7 @@ 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:481`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:487`](../../packages/core/agent/src/types.ts)
### `agent/turn-continuation` — waterfall
@@ -161,7 +161,7 @@ Waterfall: override the turn-continuation decision via a typed ContinuationDecis
Types: [Agent](../core-data-structures/core.md)
Source: [`packages/core/agent/src/types.ts:494`](../../packages/core/agent/src/types.ts)
Source: [`packages/core/agent/src/types.ts:500`](../../packages/core/agent/src/types.ts)
## `fs/*`
docs/core-data-structures/core.md
+9 -9
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@@ -193,9 +193,9 @@ The model-facing `ToolSchema` is the wire shape; the registered `ToolDefinition`
### The request envelope: `LlmCallConfig` and the logged header
Requests are built by the loop, not shaped per call: the non-history half of a request — the `EpochHeader`: this call configuration plus the rendered system prompt, assembled tool schemas, and any request-only messages — is logged session state (`request/header` snapshot and delta events, [session.md](session.md#the-request-header-events-requestheader-and-requestheader-delta)), so every conversation request is a pure function of the session log ([reconstructability RFC](../rfc/implemented/architecture/2026-07-05-reconstructable-requests.md)). The `agent/request` waterfall receives a frozen `LlmCallConfig` seed and a listener returns a replacement to switch model or sampling; the `agent/request-messages` waterfall contributes request-only messages framing the derived history (recorded as the header's `messagePrefix`/`messageSuffix`) — the loop logs whatever the request actually uses. Loop-built requests arrive at `llm/stream` deep-frozen; mutation throws.
Requests are built by the loop, not shaped per call: the non-history half of a request — the `EpochHeader`: this call configuration plus the rendered system prompt, assembled tool schemas, and any request-only messages — is logged session state (`request/header` snapshot and delta events, [session.md](session.md#the-request-header-events-requestheader-and-requestheader-delta)), so every conversation request is a pure function of the session log ([reconstructability RFC](../rfc/implemented/architecture/2026-07-05-reconstructable-requests.md)). The `agent/request` waterfall receives a frozen `LlmCallConfig` seed and a listener returns a replacement to switch model or sampling; the `agent/request-advice` waterfall weaves request-only advice around the derived history (recorded as the header's `messagePrefix`/`messageSuffix`) — the loop logs whatever the request actually uses. Loop-built requests arrive at `llm/stream` deep-frozen; mutation throws.
On the wire, a loop-built request reads in this order: the `system` slot (the rendered prompt assembly) → `messagePrefix` (request-only `before` contributions) → the derived history — the boundary snapshot, whose tail is the newest `user/message` on a turn's first step and the previous step's tool results on later steps — → `messageSuffix` (request-only `after` contributions, the last thing the model reads). The framing arrays never enter the derived history; their durable record is the header events, and the dev invariant recomputes exactly this equation against every loop-built request.
On the wire, a loop-built request reads in this order: the `system` slot (the rendered prompt assembly) → `messagePrefix` (the request-only `before` advice) → the derived history — the boundary snapshot, whose tail is the newest `user/message` on a turn's first step and the previous step's tool results on later steps — → `messageSuffix` (the request-only `after` advice, the last thing the model reads). The advice arrays never enter the derived history; their durable record is the header events, and the dev invariant recomputes exactly this equation against every loop-built request.
FIXME(call-config-shape): revisit the exact definition of this type — which fields are genuinely epoch-level for cache purposes (`model` certainly; the sampling scalars sit here out of caution), and where provider-specific extras (reasoning options, extra body params) belong when an adapter needs them.
@@ -328,7 +328,7 @@ interface Agent {
}
```
`AgentStatus` is `'idle' | 'running' | 'disposed'`. `AgentId` is a branded string. `AgentOptions` (`model?`) is merge-extensible — plugins add creation options by declaration merging; the persona is NOT an agent option but the `dsh-system-prompt` plugin's `persona` config, shared context-wide. The `agent/*` event taxonomy (lifecycle emits incl. `agent/session-start`, the serial `agent/pre-step` surface-mutation seam, and the `agent/prompt-submit`/`agent/request`/`agent/request-messages`/`agent/step-result`/`agent/turn-continuation` waterfalls) is in [architecture.md § Event taxonomy](../architecture.md#event-taxonomy); turn/step boundaries are durable `session/event` records, not `agent/*` emits.
`AgentStatus` is `'idle' | 'running' | 'disposed'`. `AgentId` is a branded string. `AgentOptions` (`model?`) is merge-extensible — plugins add creation options by declaration merging; the persona is NOT an agent option but the `dsh-system-prompt` plugin's `persona` config, shared context-wide. The `agent/*` event taxonomy (lifecycle emits incl. `agent/session-start`, the serial `agent/pre-step` surface-mutation seam, and the `agent/prompt-submit`/`agent/request`/`agent/request-advice`/`agent/step-result`/`agent/turn-continuation` waterfalls) is in [architecture.md § Event taxonomy](../architecture.md#event-taxonomy); turn/step boundaries are durable `session/event` records, not `agent/*` emits.
## Interception decisions
@@ -365,21 +365,21 @@ type ContinuationDecision =
type SessionStartSource = 'startup' | 'resume' | 'clear' | 'compact'
```
`agent/request-messages` returns a `RequestMessages` — request-only `before`/`after` messages framing the derived history for ONE request. Not a Decision union: the seam contributes content instead of vetoing, so the shape is the contribution itself; the loop records the non-empty arrays as the header's `messagePrefix`/`messageSuffix` ([the request envelope](#the-request-envelope-llmcallconfig-and-the-logged-header)), and `deriveMessages()` never returns them:
`agent/request-advice` returns a `RequestAdvice` — the request-only advice woven around the derived history for ONE request (advice in both senses: advisory content for the model, attached before/after the join point like AOP advice, never modifying the history itself). Concretely, per request: `before` messages sit in front of the ENTIRE derived history, directly after the system slot — the conventional home for session-stable openers like an AGENTS.md digest or a skills catalog, re-contributed identically every step so the provider prefix cache holds; `after` messages follow the history's last message, closing the request. Not a Decision union: the seam contributes content instead of vetoing, so the shape is the contribution itself; the loop records the non-empty arrays as the header's `messagePrefix`/`messageSuffix` ([the request envelope](#the-request-envelope-llmcallconfig-and-the-logged-header)), and `deriveMessages()` never returns them:
```ts type-equiv
interface RequestMessages {
/** Messages placed before the derived history in the request. */
interface RequestAdvice {
/** Before-advice: messages placed ahead of the entire derived history. */
before: Message[]
/** Messages placed after the derived history in the request. */
/** After-advice: messages placed after the derived history's last message. */
after: Message[]
}
```
Listeners read the already-fixed request facts from a `RequestMessagesContext` (decide what to contribute from these; never mutate them):
Listeners read the already-fixed request facts from a `RequestAdviceContext` (decide what to contribute from these; never mutate them):
```ts type-equiv
interface RequestMessagesContext {
interface RequestAdviceContext {
/** The rendered system prompt this request will carry. */
system: string
/** The prompt assembly the system prompt was rendered from (sections + tools). */
docs/core-data-structures/session.md
+2 -2
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@@ -111,7 +111,7 @@ export interface EpochHeader {
tools?: ToolSchema[]
/**
* Request-only messages sent BEFORE the derived history (the
* `agent/request-messages` waterfall's `before` contributions). Not session
* `agent/request-advice` waterfall's `before` contributions). Not session
* history — `deriveMessages()` never returns them — so the header is their
* only durable record; absent when the request carried none.
*/
@@ -121,7 +121,7 @@ export interface EpochHeader {
}
```
Canonical form: an empty system prompt, an empty tool list, and empty request-only message arrays are ABSENT fields, matching how requests are built. `messagePrefix`/`messageSuffix` are the durable record of the `agent/request-messages` waterfall's contributions (the request is `messagePrefix + derived history + messageSuffix`); their deltas replace the array whole, an empty array encoding the transition back to absence. The other delta payloads (`SystemDelta` — a common-prefix/suffix line trim; `ToolsDelta` — name-keyed added/removed/changed) live beside the events in [`packages/core/session/src/types.ts`](../../packages/core/session/src/types.ts).
Canonical form: an empty system prompt, an empty tool list, and empty request-only message arrays are ABSENT fields, matching how requests are built. `messagePrefix`/`messageSuffix` are the durable record of the `agent/request-advice` waterfall's contributions (the request is `messagePrefix + derived history + messageSuffix`); their deltas replace the array whole, an empty array encoding the transition back to absence. The other delta payloads (`SystemDelta` — a common-prefix/suffix line trim; `ToolsDelta` — name-keyed added/removed/changed) live beside the events in [`packages/core/session/src/types.ts`](../../packages/core/session/src/types.ts).
## `SessionEvent<T>` — one log entry
docs/event-producer-consumer.md
+12 -12
View File
@@ -7,18 +7,18 @@ This matrix shows which packages dispatch each harness-owned event and which pac
| Event | Mode | Declared in | Dispatchers | Listeners |
| --- | --- | --- | --- | --- |
| `agent/created` | `emit` | [`packages/core/agent/src/types.ts:308`](../packages/core/agent/src/types.ts) | [`agent`](../packages/core/agent) (`emit`) | [`stdio-agent`](../packages/ui/stdio-agent) |
| `agent/disposed` | `emit` | [`packages/core/agent/src/types.ts:315`](../packages/core/agent/src/types.ts) | [`agent`](../packages/core/agent) (`emit`) | [`stdio-agent`](../packages/ui/stdio-agent) |
| `agent/error` | `emit` | [`packages/core/agent/src/types.ts:506`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | - |
| `agent/pre-step` | `serial` | [`packages/core/agent/src/types.ts:393`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`serial`) | [`compact-basic`](../packages/compact/compact-basic) |
| `agent/prompt-submit` | `waterfall` | [`packages/core/agent/src/types.ts:406`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex) |
| `agent/queued` | `emit` | [`packages/core/agent/src/types.ts:333`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | - |
| `agent/request` | `waterfall` | [`packages/core/agent/src/types.ts:430`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | - |
| `agent/request-messages` | `waterfall` | [`packages/core/agent/src/types.ts:471`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | - |
| `agent/session-start` | `emit` | [`packages/core/agent/src/types.ts:348`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex) |
| `agent/status` | `emit` | [`packages/core/agent/src/types.ts:324`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | [`acp`](../packages/ui/acp), [`invariants`](../packages/support/invariants), [`stdio-agent`](../packages/ui/stdio-agent) |
| `agent/step-result` | `waterfall` | [`packages/core/agent/src/types.ts:481`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | - |
| `agent/turn-continuation` | `waterfall` | [`packages/core/agent/src/types.ts:494`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex) |
| `agent/created` | `emit` | [`packages/core/agent/src/types.ts:313`](../packages/core/agent/src/types.ts) | [`agent`](../packages/core/agent) (`emit`) | [`stdio-agent`](../packages/ui/stdio-agent) |
| `agent/disposed` | `emit` | [`packages/core/agent/src/types.ts:320`](../packages/core/agent/src/types.ts) | [`agent`](../packages/core/agent) (`emit`) | [`stdio-agent`](../packages/ui/stdio-agent) |
| `agent/error` | `emit` | [`packages/core/agent/src/types.ts:512`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | - |
| `agent/pre-step` | `serial` | [`packages/core/agent/src/types.ts:398`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`serial`) | [`compact-basic`](../packages/compact/compact-basic) |
| `agent/prompt-submit` | `waterfall` | [`packages/core/agent/src/types.ts:411`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex) |
| `agent/queued` | `emit` | [`packages/core/agent/src/types.ts:338`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | - |
| `agent/request` | `waterfall` | [`packages/core/agent/src/types.ts:435`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | - |
| `agent/request-advice` | `waterfall` | [`packages/core/agent/src/types.ts:477`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | - |
| `agent/session-start` | `emit` | [`packages/core/agent/src/types.ts:353`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex) |
| `agent/status` | `emit` | [`packages/core/agent/src/types.ts:329`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`emit`) | [`acp`](../packages/ui/acp), [`invariants`](../packages/support/invariants), [`stdio-agent`](../packages/ui/stdio-agent) |
| `agent/step-result` | `waterfall` | [`packages/core/agent/src/types.ts:487`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | - |
| `agent/turn-continuation` | `waterfall` | [`packages/core/agent/src/types.ts:500`](../packages/core/agent/src/types.ts) | [`agent-loop`](../packages/core/agent-loop) (`waterfall`) | [`hooks-claude`](../packages/hooks/hooks-claude), [`hooks-codex`](../packages/hooks/hooks-codex) |
| `fs/edit-intent` | `waterfall` | [`packages/fs/fs/src/index.ts:123`](../packages/fs/fs/src/index.ts) | [`tool-fs`](../packages/fs/tool-fs) (`waterfall`) | [`fs-policy`](../packages/fs/fs-policy) |
| `fs/observed` | `emit` | [`packages/fs/fs/src/index.ts:138`](../packages/fs/fs/src/index.ts) | [`tool-fs`](../packages/fs/tool-fs) (`emit`) | [`fs-policy`](../packages/fs/fs-policy) |
| `fs/write-intent` | `waterfall` | [`packages/fs/fs/src/index.ts:109`](../packages/fs/fs/src/index.ts) | [`tool-fs`](../packages/fs/tool-fs) (`waterfall`) | [`fs-policy`](../packages/fs/fs-policy) |
docs/rfc/implemented/architecture/2026-07-05-reconstructable-requests.md
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@@ -22,11 +22,11 @@ Prefix-cache stability is corollary #1, not the headline: an append-only log pro
**The header.** The request's non-history half — `EpochHeader`: call config (`LlmCallConfig`: model + sampling scalars), rendered system prompt, assembled tool schemas, and any request-only messages (`messagePrefix`/`messageSuffix`, below) — is logged session state, in canonical form (empty system/tools/message arrays ≡ absent). Two log-only, turn-enclosed events in dsh-session carry it: `request/header`, a full snapshot with reason `'initial' | 'resume' | 'fallback'`, and `request/header-delta`, an amendment (`SystemDelta`: a common-prefix/suffix line trim; `ToolsDelta`: name-keyed added/removed/changed; `config`: replaced whole; `messagePrefix`/`messageSuffix`: replaced whole, an empty array encoding the transition to absence). The pure trio `foldRequestHeader` / `diffHeader` / `applyHeaderDelta` reconstructs; the live session tracks the fold with the same lazy cursor as the message cache. Snapshots anchor the fold where a fold needs anchors — conversation birth and process boundaries — and each loop instance appends one on its first request (`'initial'` when the log has none, `'resume'` otherwise, even when nothing changed: the boundary itself is a recorded fact, and cross-restart drift becomes attributable while an unchanged header resumes byte-identical). Deltas are an encoding optimization with a safety valve, never a correctness dependency: the writer verifies `applyHeaderDelta(prev, delta)` reproduces the new header exactly and records a `'fallback'` snapshot when the encoding cannot express a change (a pure tool reordering), so a well-formed log always folds.
**The loop, transmission-stateless.** Per step: render assembly (every step — value comparison needs no change-signal discipline, and a section that varies per step surfaces as a *logged* header event per step instead of a silent bust) → `agent/pre-step` (compaction's surface mutations land before derivation) → **messages snapshot, then `step/start` appended as the next operation in the same synchronous frame** → seed the call config (first request of the instance: from `AgentOptions`, so explicit options always beat the logged baseline — fork model-overrides and resume reconfiguration stay correct; afterwards: from the folded header) → the `agent/request` waterfall, re-typed `(agent, turn, step, config: LlmCallConfig, next) → LlmCallConfig` — a frozen seed and a returned replacement are ALL a listener shapes; durable content flows through the log channels (`inject()`, steering, prompt-submit `additionalContext`, sections via `system-prompt/assemble`) — → the `agent/request-messages` waterfall — request-ONLY `before`/`after` messages framing the boundary snapshot (a frozen empty seed, contributions returned as an extension of `next()`; the per-request advisory channel: content the model must see now that must NOT become history — a skills catalog, an environment reminder) — → the header event the request owes the log, carrying those contributions as `messagePrefix`/`messageSuffix` (no session event carries them, so the header is their only durable record) → build `GenerateOptions` from `messagePrefix + snapshot + messageSuffix` + header, deep-freeze (`deepFreeze` exempts the `AbortSignal`, the one live control channel — freezing one breaks `AbortController.abort()`), dispatch. The loop's only in-process bookkeeping is one boolean: whether this instance has logged its anchoring snapshot.
**The loop, transmission-stateless.** Per step: render assembly (every step — value comparison needs no change-signal discipline, and a section that varies per step surfaces as a *logged* header event per step instead of a silent bust) → `agent/pre-step` (compaction's surface mutations land before derivation) → **messages snapshot, then `step/start` appended as the next operation in the same synchronous frame** → seed the call config (first request of the instance: from `AgentOptions`, so explicit options always beat the logged baseline — fork model-overrides and resume reconfiguration stay correct; afterwards: from the folded header) → the `agent/request` waterfall, re-typed `(agent, turn, step, config: LlmCallConfig, next) → LlmCallConfig` — a frozen seed and a returned replacement are ALL a listener shapes; durable content flows through the log channels (`inject()`, steering, prompt-submit `additionalContext`, sections via `system-prompt/assemble`) — → the `agent/request-advice` waterfall — request-ONLY `before`/`after` messages framing the boundary snapshot (a frozen empty seed, contributions returned as an extension of `next()`; the per-request advisory channel: content the model must see now that must NOT become history — a skills catalog, an environment reminder) — → the header event the request owes the log, carrying those contributions as `messagePrefix`/`messageSuffix` (no session event carries them, so the header is their only durable record) → build `GenerateOptions` from `messagePrefix + snapshot + messageSuffix` + header, deep-freeze (`deepFreeze` exempts the `AbortSignal`, the one live control channel — freezing one breaks `AbortController.abort()`), dispatch. The loop's only in-process bookkeeping is one boolean: whether this instance has logged its anchoring snapshot.
**The reconstruction boundary is `step/start`, unconditionally.** A step's messages are the derivation over `events[0..stepStartSeq)`. Because the snapshot precedes the `step/start` append in the same synchronous frame, nothing can enter this request past the boundary: an `agent.inject()` from an `agent/request` listener (or any concurrent task, or a `session/event` listener firing on `step/start` itself) lands in the log after the boundary and joins the NEXT request. For waterfall-window appends this matches the prior loop (it also derived before its waterfall); for a synchronous `step/start` listener it is a deliberate change — such a listener could previously reach the current request — and `agent/pre-step` is the sanctioned seam for content that must affect the CURRENT request. A step's header for reconstruction is the fold after its own `request/header*` event (which sits between its `step/start` and first response event) or the fold carried forward.
**Enforcement.** Dev-mode ([dsh-invariants](../../../../packages/support/invariants/src/index.ts)), on `llm/stream`: a frozen request with a live `sessionId` — the loop-built marker; hand-built one-shots are unfrozen and skipped — must carry messages deep-equal to the folded header's `messagePrefix`, then the boundary derivation, then its `messageSuffix` — the derivation rebuilt through a FRESH `Session` over `events[0..stepStartSeq)` so the live cache cannot vouch for itself — and header fields equal to `foldRequestHeader` over the log. There is no divergence allowance and nothing to allow: no seam can put unlogged content into a request — the `agent/request-messages` seam's contributions enter only because the header event records them first. `prepend: true` only defends against the replay adapter's short-circuit (an append-registered listener); two prepended listeners have no defined mutual order in cordis, so correctness rests on the seq-bounded fold, never on listener timing. Measurement stays lean: the with-key e2e ([request-cache.e2e.ts](../../../../packages/core/agent-loop/tests/request-cache.e2e.ts)) proves `usage.cacheReadTokens > 0` on every request after the first against the live API, and per-step usage in the log is the production observable — a header event or compaction shows up as a cache-read collapse on the next step.
**Enforcement.** Dev-mode ([dsh-invariants](../../../../packages/support/invariants/src/index.ts)), on `llm/stream`: a frozen request with a live `sessionId` — the loop-built marker; hand-built one-shots are unfrozen and skipped — must carry messages deep-equal to the folded header's `messagePrefix`, then the boundary derivation, then its `messageSuffix` — the derivation rebuilt through a FRESH `Session` over `events[0..stepStartSeq)` so the live cache cannot vouch for itself — and header fields equal to `foldRequestHeader` over the log. There is no divergence allowance and nothing to allow: no seam can put unlogged content into a request — the `agent/request-advice` seam's contributions enter only because the header event records them first. `prepend: true` only defends against the replay adapter's short-circuit (an append-registered listener); two prepended listeners have no defined mutual order in cordis, so correctness rests on the seq-bounded fold, never on listener timing. Measurement stays lean: the with-key e2e ([request-cache.e2e.ts](../../../../packages/core/agent-loop/tests/request-cache.e2e.ts)) proves `usage.cacheReadTokens > 0` on every request after the first against the live API, and per-step usage in the log is the production observable — a header event or compaction shows up as a cache-read collapse on the next step.
### The MiniCode shape: adopted, with the provenance arrow inverted
@@ -44,7 +44,7 @@ What survives from `LLMClient`: the conversation is maintained, not rebuilt —
## Consequences
- A request that is not explained by the log cannot be constructed by accident — not by the loop, not by a listener; mutating a built request throws; every header change is a durable, diffable log event.
- Choosing between the advisory channels is a change-frequency cost decision, and the seam does not hide it: an `agent/request-messages` contribution rides the request's uncached tail and is re-tokenized at full price on every request it appears in (a `before` contribution instead extends the cacheable prefix at zero marginal cost while stable, but a mid-session change invalidates the provider cache for the entire history after it), whereas an `inject()`ed `context/message` is paid once and prefix-cached thereafter at the price of accumulating durably in history and the log. Route session-frozen content to `before`, low-frequency change notices to `inject()`, and reserve `after` for small, frequently refreshed state snapshots where a durable chain of stale copies would bloat the log and mislead the model.
- Choosing between the advisory channels is a change-frequency cost decision, and the seam does not hide it: an `agent/request-advice` contribution rides the request's uncached tail and is re-tokenized at full price on every request it appears in (a `before` contribution instead extends the cacheable prefix at zero marginal cost while stable, but a mid-session change invalidates the provider cache for the entire history after it), whereas an `inject()`ed `context/message` is paid once and prefix-cached thereafter at the price of accumulating durably in history and the log. Route session-frozen content to `before`, low-frequency change notices to `inject()`, and reserve `after` for small, frequently refreshed state snapshots where a durable chain of stale copies would bloat the log and mislead the model.
- What still costs full price at the provider is inherent and logged: compaction (its `compact/*` events and replace node), a real prompt/tool change (`request/header-delta`), a config switch (ditto), a process boundary with drift (`'resume'` snapshot differing from its predecessor). The provider's own reasoning-content exclusion is managed server-side.
- The `step/start`-listener behavior change (above) is the one observable semantics change for plugins; `agent/pre-step` is the current-request seam.
- Tool-result trimming (planned) needs no new mechanism: a logged single-node surface replace (`start === end`) carrying a trimmed `tool/result` under the same `callId` — compaction-family, replay-correct, cache-bust batched by the same pressure logic.