Adapt workspace context to session prefixes

packages/core/session/README.md

@@ -53,6 +53,8 @@ Plain class (not a Cordis Service). Create via `ctx.sessions.create()`.
 
 The `request/header` (full `EpochHeader` snapshot with a `RequestHeaderReason`) and `request/header-delta` (system line-trim / name-keyed tools delta / whole config / whole session prefix) events make the request envelope logged session state, so every conversation request is a pure function of the log. The pure trio reconstructs it: `foldRequestHeader(events)` folds a log (or any prefix) into the header in force; `diffHeader(prev, next)` encodes a change (undefined when equal); `applyHeaderDelta(prev, delta)` replays one. Writer contract: every logged delta is round-trip-verified (`apply(prev, delta)` deep-equals the new header) with a `'fallback'` snapshot when the encoding cannot express the change (a pure tool reordering), so folding never needs error recovery on a well-formed log. `canonicalHeader` pins the one representation of absence (empty system/tools/messagePrefix ≡ absent fields; a delta's EMPTY prefix array encodes the transition back to absence). `EpochHeader.messagePrefix` is the durable record of the `agent/session-prefix` waterfall's product — composed once per loop instance, the request is `messagePrefix + derived history`, and `deriveMessages()` never returns it.
 
+`context/message` defaults to the canonical tagged context projection. A producer may set `envelope: 'raw'` when its `content` already contains the complete model-facing frame, and may attach JSON `meta` for replayable plugin state; metadata remains durable but is excluded from `deriveMessages()`.
+
 ### Session event vocabulary (`types.ts`)
 
 The append-only log's event types, enumerated member by member — payloads, surface badges, provenance — in the generated [persistence log event catalog](../../../docs/persistence-catalog.md). Token usage rides on `assistant/message.usage`; an operational error's step is on `turn/end.reason` for `kind: 'error'`.

packages/core/session/src/index.ts

@@ -11,7 +11,7 @@ import { isAbsolute } from 'node:path'
 import { deepFreeze } from '@deepseek-ai/dsh-llm'
 import type { ContentBlock, Message, MessageSource } from '@deepseek-ai/dsh-llm'
 import { SESSION_FORMAT_VERSION, SessionId } from './types.ts'
-import type { CreateSessionOptions, EpochHeader, SessionEvent, SessionEventMap, SessionEventType, SessionHeader, SurfaceIntent, SurfaceEventType } from './types.ts'
+import type { ContextEnvelope, CreateSessionOptions, EpochHeader, SessionEvent, SessionEventMap, SessionEventType, SessionHeader, SurfaceIntent, SurfaceEventType } from './types.ts'
 import { isJsonValue } from './json.ts'
 import { SurfaceManager, isSurfaceEligibleType } from './surface.ts'
 import { foldRequestHeader } from './request-header.ts'
@@ -77,6 +77,22 @@ function renderTagged(tag: string, content: ContentBlock[], source: MessageSourc
   ]
 }
 
+/**
+ * Render one context contribution exactly as it will appear in model history.
+ * @param content - content blocks supplied by the context producer.
+ * @param source - attribution used by the canonical context envelope.
+ * @param envelope - canonical tagged framing or caller-owned raw framing.
+ * @returns a detached block list ready for the derived model transcript.
+ */
+export function renderContextContent(
+  content: ContentBlock[],
+  source: MessageSource,
+  envelope: ContextEnvelope = 'context',
+): ContentBlock[] {
+  const cloned = structuredClone(content)
+  return envelope === 'raw' ? cloned : renderTagged('context', cloned, source)
+}
+
 /**
  * An event-sourced session: an append-only log of {@link SessionEvent}s.
  *
@@ -355,8 +371,8 @@ export class Session {
         }
       }
       case 'context/message': {
-        const { content, source } = event.data
-        return { role: 'user', content: renderTagged('context', structuredClone(content), source) }
+        const { content, source, envelope } = event.data
+        return { role: 'user', content: renderContextContent(content, source, envelope) }
       }
       case 'steering/message': {
         const { content, source } = event.data

packages/core/session/src/types.ts

@@ -1,5 +1,9 @@
 import type { Branded } from '@deepseek-ai/dsh-brand'
 import type { CallId, ContentBlock, LlmCallConfig, Message, MessageSource, StreamChunk, TokenUsage, ToolSchema } from '@deepseek-ai/dsh-llm'
+import type { JsonValue } from './json.ts'
+
+/** Canonical context-tag framing, or caller-owned framing rendered verbatim. */
+export type ContextEnvelope = 'context' | 'raw'
 
 /** Identifies one session in the store (and its persistence artifacts). */
 export type SessionId = Branded<'SessionId'>
@@ -306,9 +310,16 @@ export interface SessionEventMap {
   /**
    * In-session context injection (file-change notices, subdir AGENTS.md,
    * skill content, cron notifications, …). Rendered into the derived history
-   * as tagged synthetic context — NOT a user prompt.
+   * as synthetic context — NOT a user prompt. `envelope: 'raw'` lets a caller
+   * own the complete model-facing frame; `meta` is durable JSON state omitted
+   * from the model projection.
    */
-  'context/message': { content: ContentBlock[]; source: MessageSource }
+  'context/message': {
+    content: ContentBlock[]
+    source: MessageSource
+    envelope?: ContextEnvelope
+    meta?: JsonValue
+  }
   /** Raw stream chunk — token-level replay fidelity. */
   'assistant/chunk': { turn: number; step: number; chunk: StreamChunk }
   /**

packages/core/session/tests/session.spec.ts

@@ -59,6 +59,28 @@ describe('Session', () => {
     expect(steeringMessage!.content[0]).toMatchObject({ type: 'text', text: '<steering source="user">' })
   })
 
+  it('renders raw context without a generic envelope while preserving structured metadata', () => {
+    const session = new Session(SessionId('s2-raw'))
+    const meta = {
+      kind: 'workspace-instructions',
+      version: 1,
+      changes: [{ action: 'set', scope: 'pkg', path: 'pkg/AGENTS.md', digest: 'abc123' }],
+    }
+    session.append('context/message', {
+      content: [{ type: 'text', text: '<system-reminder>Additional instructions from: pkg/AGENTS.md</system-reminder>' }],
+      source: { kind: 'plugin', plugin: 'workspace-context' },
+      envelope: 'raw',
+      meta,
+    }, { surfaceOp: 'append' })
+
+    expect(session.deriveMessages()).toEqual([{
+      role: 'user',
+      content: [{ type: 'text', text: '<system-reminder>Additional instructions from: pkg/AGENTS.md</system-reminder>' }],
+    }])
+    const event = session.events[0]
+    expect(event?.type === 'context/message' && event.data.meta).toEqual(meta)
+  })
+
   it('replays identically from a seeded event log', () => {
     const original = new Session(SessionId('s3'))
     original.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })