chore: switch all subagent models to auto/auto-fast (#1436)

Co-authored-by: Letta Code <noreply@letta.com>

src/agent/subagents/builtin/explore.md

@@ -2,7 +2,7 @@
 name: explore
 description: Fast agent for codebase exploration - finding files, searching code, understanding structure. (Read-Only)
 tools: Glob, Grep, Read, TaskOutput
-model: haiku
+model: auto-fast
 memoryBlocks: human, persona
 mode: stateless
 ---

src/agent/subagents/builtin/general-purpose.md

@@ -2,7 +2,7 @@
 name: general-purpose
 description: Full-capability agent for research, planning, and implementation
 tools: Bash, TaskOutput, Edit, Glob, Grep, KillBash, LS, MultiEdit, Read, TodoWrite, Write
-model: sonnet
+model: auto
 memoryBlocks: all
 mode: stateful
 ---

src/agent/subagents/builtin/history-analyzer.md

@@ -3,7 +3,7 @@ name: history-analyzer
 description: Analyze Claude Code or Codex conversation history and directly update agent memory files with insights
 tools: Read, Write, Bash, Glob, Grep
 skills: migrating-from-codex-and-claude-code
-model: sonnet
+model: auto
 memoryBlocks: none
 mode: stateless
 permissionMode: bypassPermissions

src/agent/subagents/builtin/init.md

@@ -2,7 +2,7 @@
 name: init
 description: Fast initialization of agent memory — reads key project files and creates a minimal memory hierarchy
 tools: Read, Write, Edit, Bash, Glob
-model: haiku
+model: auto-fast
 memoryBlocks: none
 permissionMode: bypassPermissions
 ---

src/agent/subagents/builtin/memory.md

@@ -2,7 +2,7 @@
 name: memory
 description: Decompose and reorganize memory files into focused, single-purpose files using `/` naming
 tools: Read, Edit, Write, Glob, Grep, Bash, TaskOutput
-model: sonnet
+model: auto
 memoryBlocks: none
 permissionMode: bypassPermissions
 ---

src/agent/subagents/builtin/reflection.md

@@ -2,7 +2,7 @@
 name: reflection
 description: Background agent that reflects on recent conversations and updates memory files
 tools: Read, Edit, Write, Glob, Grep, Bash, TaskOutput
-model: sonnet
+model: auto
 memoryBlocks: none
 mode: stateless
 permissionMode: bypassPermissions

src/tests/cli/init-background-subagent.test.ts

@@ -49,7 +49,7 @@ describe("init wiring", () => {
     const content = readSource("../../agent/subagents/builtin/init.md");
 
     expect(content).toContain("name: init");
-    expect(content).toContain("model: haiku");
+    expect(content).toContain("model: auto-fast");
     expect(content).toContain("permissionMode: bypassPermissions");
   });
 
@@ -62,11 +62,11 @@ describe("init wiring", () => {
     expect(indexSource).toContain("initAgentMd");
   });
 
-  test("init.md uses haiku model and no skills", () => {
+  test("init.md uses auto-fast model and no skills", () => {
     const content = readSource("../../agent/subagents/builtin/init.md");
 
     expect(content).toContain("name: init");
-    expect(content).toContain("model: haiku");
+    expect(content).toContain("model: auto-fast");
     expect(content).not.toContain("skills:");
     expect(content).toContain("permissionMode: bypassPermissions");
   });