refactor(agent): unify sourced message delivery

packages/context/session-reference/README.md

@@ -5,7 +5,7 @@
 ## Public API
 
 - `listCandidates(agent, query?, limit?)` lists sessions other than `agent.id`, filters case-insensitively by id or cwd, and ranks same-cwd, cwd-less, then other-cwd records while preserving `listSessions()` creation order within each group. Each selected candidate uses its latest log-backed title as the mention label and falls back to the session id; titles and message bodies are not searched.
-- `prepare(agent, content, references, signal?)` preserves first-mention order, deduplicates ids, rejects self-reference and more than the configured distinct-source limit, reads every source in parallel, and returns detached content plus zero or one aggregated `AdditionalContext`. Any invalid reference, failed read, cancellation, or budget failure rejects before the host injects context and sends or steers the direct message.
+- `prepare(agent, content, references, signal?)` preserves first-mention order, deduplicates ids, rejects self-reference and more than the configured distinct-source limit, reads every source in parallel, and returns detached content plus zero or one aggregated `UserMessageData` context. Any invalid reference, failed read, cancellation, or budget failure rejects before the host injects context and sends or steers the direct message.
 - `encodeSessionReferenceUri()` and `decodeSessionReferenceUri()` implement `dsh-session:<base64url(JSON.stringify(sessionId))>` so every JavaScript string id round-trips exactly. `formatSessionReferenceMention()` emits `@[label](uri)`, and `parseSessionReferenceText()` replaces Markdown mentions or bare canonical URIs with readable `@label` text while returning structured references. Explicit Markdown mentions reject every malformed URI; bare text is considered a reference only when a non-empty base64url-shaped payload follows the scheme, and a matching noncanonical candidate still fails. Empty or punctuation-only scheme mentions remain ordinary discussion text.
 
 ## Snapshot semantics

packages/context/session-reference/src/index.ts

@@ -7,9 +7,9 @@
 
 import { Context, Service } from 'cordis'
 import z from 'schemastery'
-import type { AdditionalContext, Agent } from '@deepseek-ai/dsh-agent'
+import type { Agent } from '@deepseek-ai/dsh-agent'
 import type { ContentBlock } from '@deepseek-ai/dsh-llm'
-import type { SessionId } from '@deepseek-ai/dsh-session'
+import type { SessionId, UserMessageData } from '@deepseek-ai/dsh-session'
 import type { SessionSurfaceSnapshot } from '@deepseek-ai/dsh-session-query'
 import {
   DEFAULT_CANDIDATE_LIMIT,
@@ -192,7 +192,7 @@ export class SessionReferenceService extends Service {
         inputIndex: index,
       })),
     }
-    const additionalContext: AdditionalContext = {
+    const additionalContext: UserMessageData = {
       source,
       content: [{ type: 'text', text: prompt }],
     }

packages/context/session-reference/src/types.ts

@@ -1,8 +1,7 @@
 /** Public session-reference request, candidate, and preparation records. */
 
-import type { AdditionalContext } from '@deepseek-ai/dsh-agent'
 import type { ContentBlock } from '@deepseek-ai/dsh-llm'
-import type { SessionId } from '@deepseek-ai/dsh-session'
+import type { SessionId, UserMessageData } from '@deepseek-ai/dsh-session'
 
 /** Durable provenance for one prepared cross-session context. */
 export interface SessionReferenceSource {
@@ -53,7 +52,7 @@ export interface PreparedReferencedMessage {
   /** Readable message content after host mention tokens are removed. */
   content: ContentBlock[]
   /** Aggregated untrusted snapshot, absent when the message has no references. */
-  additionalContext?: AdditionalContext
+  additionalContext?: UserMessageData
 }
 
 /** Text-only projected conversation item. */