fix(session): drop the <context> envelope and project context verbatim

context/message previously defaulted to a <context source="…">…</context>
wrapper. No model is trained on a <context> tag either, and message
framing does not belong on the session surface: the surface projects the
durable log, and a caller that wants a frame formats its own content —
which the one heavy producer (workspace-context) already does with its own
<system-reminder> frame, opting out via 'raw'. The tag only added
machinery — ContextEnvelope plus an envelope field threaded through
InjectOptions, HookContext, the context/message event, and the agent-loop
inject/additionalContexts plumbing.

context/message now projects its content verbatim as a user-role message,
sharing one deriveEventMessage case with user/message and steering/message.
ContextEnvelope and every envelope field are removed; context/message.meta
still carries durable, model-hidden JSON state. Regenerated catalogs and
website API; refreshed the three affected keyless snapshots (envelope field
only; timestamps unchanged).

Broadens and renames the steering Agent Note to cover both envelope
removals as one decision.

Agent Note: .agents/notes/implemented/simplification/2026-07-20-unwrap-injected-content-envelopes.md

packages/context/workspace-context/README.md

@@ -42,7 +42,7 @@ These instructions apply to work under `packages/app`. Use them as guidance when
 
 A same-file edit starts with `Updated instructions from: <path>` and says to use the new content instead of the previously loaded content. A candidate switch additionally names the old path. When no candidate remains, the message is `Instructions removed: <path>` followed by `The previously loaded instructions from this file no longer apply.` Literal `</system-reminder>` text inside an instruction file is escaped so file content cannot close the plugin-owned frame.
 
-The core `context/message` envelope is disabled for these messages because the plugin already owns the complete `<system-reminder>` framing. This is caller-selected with `envelope: 'raw'`; ordinary injected context still receives the canonical `<context source="...">` envelope.
+The plugin owns the complete `<system-reminder>` framing, and every `context/message` (from this plugin or any other) reaches the model verbatim as a user-role message with no wrapping.
 
 ## State And Refresh
 

packages/context/workspace-context/src/index.ts

@@ -92,7 +92,6 @@ export function apply(ctx: Context, config: Config): void {
     if (update !== undefined) {
       agent.inject(update.context.content, {
         source: update.context.source,
-        envelope: update.context.envelope,
         meta: update.context.meta,
       })
       applyInstructionVersionUpdates(agent.session, update.versionUpdates, instructionVersions)

packages/context/workspace-context/src/render.ts

@@ -163,6 +163,12 @@ function buildInstructionText(
 ): string {
   const marker = markerText(maxBytes, omitted, truncated)
   const body = [marker, style.intro, ...files.map(file => style.section(file))].filter(block => block.length > 0)
+  // Caller-owned framing: the plugin bakes the complete `<system-reminder>`
+  // frame into the message content. The session surface projects context
+  // verbatim and does not wrap it, so any framing must live here in the
+  // producer's content (the pattern a future `meta`-driven renderer would
+  // generalize — see the deferred note in
+  // ../../../../.agents/notes/implemented/simplification/2026-07-20-unwrap-injected-content-envelopes.md).
   return [SYSTEM_REMINDER_OPEN, body.join('\n\n'), SYSTEM_REMINDER_CLOSE].join('\n')
 }
 

packages/context/workspace-context/src/state.ts

@@ -61,9 +61,8 @@ export interface ReconciledInstructionContext {
   versionUpdates: InstructionVersionUpdate[]
 }
 
-/** Plugin-owned raw context with required replay metadata. */
+/** Plugin-owned context with required replay metadata. */
 export interface WorkspaceHookContext extends HookContext {
-  envelope: 'raw'
   meta: JsonValue
 }
 
@@ -76,7 +75,7 @@ function workspaceContextHook(text: string, changes: WorkspaceInstructionChange[
     ...change.digest !== undefined ? { digest: change.digest } : {},
   }))
   const meta: JsonValue = { kind: 'workspace-instructions', version: 1, changes: serializedChanges }
-  return { content: [{ type: 'text', text }], source: PLUGIN_SOURCE, envelope: 'raw', meta }
+  return { content: [{ type: 'text', text }], source: PLUGIN_SOURCE, meta }
 }
 
 /**

packages/context/workspace-context/tests/workspace-context.spec.ts

@@ -173,7 +173,6 @@ function stubAgent(cwd?: string, seed: SessionEvent[] = []): Agent {
       session.append('context/message', {
         content,
         source: options?.source ?? { kind: 'user' },
-        ...options?.envelope !== undefined ? { envelope: options.envelope } : {},
         ...options?.meta !== undefined ? { meta: options.meta } : {},
       }, { surfaceOp: 'append' })
     },
@@ -202,7 +201,6 @@ function workspaceChangeContext(scope: string, digest: string): HookContext {
   return {
     content: [{ type: 'text', text: `instructions for ${scope}` }],
     source: { kind: 'plugin', plugin: 'workspace-context' },
-    envelope: 'raw',
     meta: {
       kind: 'workspace-instructions',
       version: 1,
@@ -217,7 +215,6 @@ function appendAdditionalContexts(agent: Agent, result: { additionalContexts?: H
     lastSeq = agent.session.append('context/message', {
       content: context.content,
       source: context.source,
-      ...context.envelope !== undefined ? { envelope: context.envelope } : {},
       ...context.meta !== undefined ? { meta: context.meta } : {},
     }, { surfaceOp: 'append' }).seq
   }
@@ -1695,7 +1692,6 @@ describe('dynamic nested workspace context injection', () => {
 
       expect(result.isError).toBe(false)
       expect(workspaceContextOf(result)?.source).toEqual({ kind: 'plugin', plugin: 'workspace-context' })
-      expect(workspaceContextOf(result)?.envelope).toBe('raw')
       expect(workspaceContextOf(result)?.meta).toMatchObject({
         kind: 'workspace-instructions',
         version: 1,
@@ -2461,7 +2457,6 @@ describe('dynamic nested workspace context injection', () => {
       expect(blocksText(result.content)).toBe('downstream replacement')
       expect(result.additionalContexts).toHaveLength(2)
       expect(workspaceContextOf(result)?.source).toEqual({ kind: 'plugin', plugin: 'workspace-context' })
-      expect(workspaceContextOf(result)?.envelope).toBe('raw')
       expect(workspaceContextOf(result)?.meta).toMatchObject({
         kind: 'workspace-instructions',
         changes: [{ action: 'set', scope: 'pkg', path: 'pkg/AGENTS.md' }],
@@ -2474,7 +2469,8 @@ describe('dynamic nested workspace context injection', () => {
       })
       const agent = stubAgent(root)
       appendAdditionalContexts(agent, result)
-      expect(blocksText(agent.session.deriveMessages()[1]?.content)).toContain('<context source="plugin">\ndownstream context\n</context>')
+      expect(blocksText(agent.session.deriveMessages()[1]?.content)).toContain('downstream context')
+      expect(blocksText(agent.session.deriveMessages()[1]?.content)).not.toContain('<context source=')
     } finally {
       await rm(root, { recursive: true, force: true })
       await rm(home, { recursive: true, force: true })
@@ -2807,7 +2803,6 @@ describe('workspace context pending state', () => {
     const otherWorkspaceEvent = agent.session.append('context/message', {
       content: otherContext.content,
       source: otherContext.source,
-      ...otherContext.envelope !== undefined ? { envelope: otherContext.envelope } : {},
       ...otherContext.meta !== undefined ? { meta: otherContext.meta } : {},
     }, { surfaceOp: 'append' })
     observeInstructionSessionEvent(agent.session, otherWorkspaceEvent, pending, versions)
@@ -2817,7 +2812,6 @@ describe('workspace context pending state', () => {
     const confirmed = agent.session.append('context/message', {
       content: context.content,
       source: context.source,
-      ...context.envelope !== undefined ? { envelope: context.envelope } : {},
       ...context.meta !== undefined ? { meta: context.meta } : {},
     }, { surfaceOp: 'append' })
     observeInstructionSessionEvent(agent.session, confirmed, pending, versions)