feat(agent): unify send(target × wakeup), coalesce context/message into user/message

Replace send/steer/inject with one Agent.send primitive over the
(target × wakeup) matrix; followup/steer/inject become fixed-preset
alias methods on the now-abstract Agent class. Coalesce context/message
into user/message (injected context is a non-user source). Replace
agent/queued with agent/inbox/enqueue/dequeue/discard, add cancel
keepInbox, and add a FIFO-conservation invariant.

scripts/gen-cordis-catalog.ts

@@ -36,6 +36,7 @@ export const LINK_MAP: Record<string, string> = {
   ContinuationStop: 'core.md',
   GenerateOptions: 'core.md',
   HookContext: 'core.md',
+  InboxItemInfo: 'core.md',
   LlmCallConfig: 'core.md',
   LlmModelContext: 'core.md',
   LlmFailure: 'llm-streaming.md',

scripts/gen-doc-graphs.ts

@@ -911,7 +911,7 @@ function renderLifecycle(): string {
     '  participant Persistence',
     '  participant SDK as UI or SDK listener',
     '  User->>Agent: send(content)',
-    `  Agent-->>SDK: ${mermaidCode('agent/queued')}`,
+    `  Agent-->>SDK: ${mermaidCode('agent/inbox/enqueue')}`,
     '  Agent->>Driver: queued work wakes driver',
     `  Driver-->>SDK: ${mermaidCode('agent/status')} running`,
     `  Driver->>Session: ${mermaidCode('turn/start')}`,
@@ -988,7 +988,7 @@ function renderToolPipeline(): string {
     `  owned["Tool-owned session events<br/>${mermaidCode('todo/write')}, ${mermaidCode('fs/observed')}, ${mermaidCode('hook/invoked')}, ${mermaidCode('hook/result')}, ${mermaidCode('tool/code-dispatch')}"]`,
     `  post["${mermaidCode('tools/post-execute')} waterfall<br/>accept, block, replace, add context"]`,
     `  final["${mermaidCode('tools/result')} synchronous notification<br/>frozen authoritative outcome"]`,
-    '  context["Active-batch additionalContexts FIFO<br/>context/message after recorded tool results"]',
+    '  context["Active-batch additionalContexts FIFO<br/>injected user/message after recorded tool results"]',
     `  toolResult["Session event: ${mermaidCode('tool/result')}<br/>single model-facing outcome"]`,
     '  allResults["Tool batch settled<br/>recorded tool/result events complete"]',
     '  presentResult["UI completed card<br/>presentResult(args, result)"]',

scripts/gen-tool-catalog.ts

@@ -263,7 +263,7 @@ const TOOL_PACKAGES: ToolPackage[] = [
     dir: 'tool-goal',
     source: 'packages/goal/tool-goal/src/index.ts',
     requires: ['ctx.tools', 'ctx.agents', 'ctx.goals', 'ctx.systemPrompt', 'a calling Agent in an authorized open turn'],
-    writes: ['tool/call', 'context/message goal snapshot for mutations', 'tool/result'],
+    writes: ['tool/call', 'user/message goal snapshot for mutations', 'tool/result'],
     async mount(ctx) {
       await ctx.plugin(AgentRegistry)
       await ctx.plugin(GoalService)
@@ -336,7 +336,7 @@ const TOOL_PACKAGES: ToolPackage[] = [
     dir: 'tool-tasks',
     source: 'packages/tasks/tool-tasks/src/index.ts',
     requires: ['ctx.tools', 'ctx.tasks', 'ctx.systemPrompt'],
-    writes: ['tool/call', 'tool/result', 'context/message via agent.inject() for background completion notices'],
+    writes: ['tool/call', 'tool/result', 'user/message via agent.inject() for background completion notices'],
     async mount(ctx) {
       await ctx.plugin(TaskService)
       await ctx.plugin(ToolTasks)

scripts/type-equiv.manifest.json

@@ -66,6 +66,11 @@
       "symbol": "SessionEvent",
       "source": "packages/core/session/src/types.ts"
     },
+    {
+      "doc": "docs/core-data-structures/core.md",
+      "symbol": "SendTarget",
+      "source": "packages/core/agent/src/types.ts"
+    },
     {
       "doc": "docs/core-data-structures/core.md",
       "symbol": "SendOptions",
@@ -73,12 +78,22 @@
     },
     {
       "doc": "docs/core-data-structures/core.md",
-      "symbol": "AgentCancelCause",
+      "symbol": "AliasSendOptions",
       "source": "packages/core/agent/src/types.ts"
     },
     {
       "doc": "docs/core-data-structures/core.md",
-      "symbol": "InjectOptions",
+      "symbol": "InboxItemInfo",
+      "source": "packages/core/agent/src/types.ts"
+    },
+    {
+      "doc": "docs/core-data-structures/core.md",
+      "symbol": "CancelOptions",
+      "source": "packages/core/agent/src/types.ts"
+    },
+    {
+      "doc": "docs/core-data-structures/core.md",
+      "symbol": "AgentCancelCause",
       "source": "packages/core/agent/src/types.ts"
     },
     {