diff --git a/src/agents/types.ts b/src/agents/types.ts
index 4169895cb..f22683a27 100644
--- a/src/agents/types.ts
+++ b/src/agents/types.ts
@@ -64,7 +64,7 @@ export type BuiltinAgentName =
   | "multimodal-looker"
   | "Metis (Plan Consultant)"
   | "Momus (Plan Reviewer)"
-  | "atlas"
+  | "Atlas"
 
 export type OverridableAgentName =
   | "build"
diff --git a/src/agents/utils.ts b/src/agents/utils.ts
index bb691b59e..6bc3c5d86 100644
--- a/src/agents/utils.ts
+++ b/src/agents/utils.ts
@@ -25,9 +25,9 @@ const agentSources: Record<BuiltinAgentName, AgentSource> = {
   "multimodal-looker": createMultimodalLookerAgent,
   "Metis (Plan Consultant)": createMetisAgent,
   "Momus (Plan Reviewer)": createMomusAgent,
-  // Note: atlas is handled specially in createBuiltinAgents()
+  // Note: Atlas is handled specially in createBuiltinAgents()
   // because it needs OrchestratorContext, not just a model string
-  atlas: createAtlasAgent as unknown as AgentFactory,
+  Atlas: createAtlasAgent as unknown as AgentFactory,
 }
 
 /**
@@ -166,7 +166,7 @@ export function createBuiltinAgents(
     const agentName = name as BuiltinAgentName
 
     if (agentName === "Sisyphus") continue
-    if (agentName === "atlas") continue
+    if (agentName === "Atlas") continue
     if (disabledAgents.includes(agentName)) continue
 
     const override = agentOverrides[agentName]
@@ -219,8 +219,8 @@ export function createBuiltinAgents(
     result["Sisyphus"] = sisyphusConfig
   }
 
-  if (!disabledAgents.includes("atlas")) {
-    const orchestratorOverride = agentOverrides["atlas"]
+  if (!disabledAgents.includes("Atlas")) {
+    const orchestratorOverride = agentOverrides["Atlas"]
     const orchestratorModel = orchestratorOverride?.model ?? systemDefaultModel
      let orchestratorConfig = createAtlasAgent({
        model: orchestratorModel,
@@ -233,7 +233,7 @@ export function createBuiltinAgents(
       orchestratorConfig = mergeAgentConfig(orchestratorConfig, orchestratorOverride)
     }
 
-    result["atlas"] = orchestratorConfig
+    result["Atlas"] = orchestratorConfig
   }
 
   return result
diff --git a/src/config/schema.ts b/src/config/schema.ts
index 5f684b572..2fdde902c 100644
--- a/src/config/schema.ts
+++ b/src/config/schema.ts
@@ -24,7 +24,7 @@ export const BuiltinAgentNameSchema = z.enum([
   "multimodal-looker",
   "Metis (Plan Consultant)",
   "Momus (Plan Reviewer)",
-  "atlas",
+  "Atlas",
 ])
 
 export const BuiltinSkillNameSchema = z.enum([
@@ -46,7 +46,7 @@ export const OverridableAgentNameSchema = z.enum([
   "librarian",
   "explore",
   "multimodal-looker",
-  "atlas",
+  "Atlas",
 ])
 
 export const AgentNameSchema = BuiltinAgentNameSchema
@@ -127,7 +127,7 @@ export const AgentOverridesSchema = z.object({
   librarian: AgentOverrideConfigSchema.optional(),
   explore: AgentOverrideConfigSchema.optional(),
   "multimodal-looker": AgentOverrideConfigSchema.optional(),
-  atlas: AgentOverrideConfigSchema.optional(),
+  Atlas: AgentOverrideConfigSchema.optional(),
 })
 
 export const ClaudeCodeConfigSchema = z.object({
diff --git a/src/features/builtin-commands/commands.ts b/src/features/builtin-commands/commands.ts
index d4e10903b..053c3eeda 100644
--- a/src/features/builtin-commands/commands.ts
+++ b/src/features/builtin-commands/commands.ts
@@ -55,7 +55,7 @@ ${REFACTOR_TEMPLATE}
   },
   "start-work": {
     description: "(builtin) Start Sisyphus work session from Prometheus plan",
-    agent: "atlas",
+    agent: "Atlas",
     template: `<command-instruction>
 ${START_WORK_TEMPLATE}
 </command-instruction>
diff --git a/src/hooks/atlas/index.test.ts b/src/hooks/atlas/index.test.ts
index 19f6db8bd..4a90f9aeb 100644
--- a/src/hooks/atlas/index.test.ts
+++ b/src/hooks/atlas/index.test.ts
@@ -85,8 +85,8 @@ describe("atlas hook", () => {
       expect(output.output).toBe("Original output")
     })
 
-     test("should not transform when caller is not atlas", async () => {
-       // #given - boulder state exists but caller agent in message storage is not atlas
+     test("should not transform when caller is not Atlas", async () => {
+       // #given - boulder state exists but caller agent in message storage is not Atlas
        const sessionID = "session-non-orchestrator-test"
        setupMessageStorage(sessionID, "other-agent")
       
@@ -120,10 +120,10 @@ describe("atlas hook", () => {
       cleanupMessageStorage(sessionID)
     })
 
-     test("should append standalone verification when no boulder state but caller is atlas", async () => {
-       // #given - no boulder state, but caller is atlas
+     test("should append standalone verification when no boulder state but caller is Atlas", async () => {
+       // #given - no boulder state, but caller is Atlas
        const sessionID = "session-no-boulder-test"
-       setupMessageStorage(sessionID, "atlas")
+       setupMessageStorage(sessionID, "Atlas")
       
       const hook = createAtlasHook(createMockPluginInput())
       const output = {
@@ -146,10 +146,10 @@ describe("atlas hook", () => {
       cleanupMessageStorage(sessionID)
     })
 
-     test("should transform output when caller is atlas with boulder state", async () => {
-       // #given - atlas caller with boulder state
+     test("should transform output when caller is Atlas with boulder state", async () => {
+       // #given - Atlas caller with boulder state
        const sessionID = "session-transform-test"
-       setupMessageStorage(sessionID, "atlas")
+       setupMessageStorage(sessionID, "Atlas")
       
       const planPath = join(TEST_DIR, "test-plan.md")
       writeFileSync(planPath, "# Plan\n- [ ] Task 1\n- [x] Task 2")
@@ -186,9 +186,9 @@ describe("atlas hook", () => {
     })
 
      test("should still transform when plan is complete (shows progress)", async () => {
-       // #given - boulder state with complete plan, atlas caller
+       // #given - boulder state with complete plan, Atlas caller
        const sessionID = "session-complete-plan-test"
-       setupMessageStorage(sessionID, "atlas")
+       setupMessageStorage(sessionID, "Atlas")
       
       const planPath = join(TEST_DIR, "complete-plan.md")
       writeFileSync(planPath, "# Plan\n- [x] Task 1\n- [x] Task 2")
@@ -223,9 +223,9 @@ describe("atlas hook", () => {
     })
 
      test("should append session ID to boulder state if not present", async () => {
-       // #given - boulder state without session-append-test, atlas caller
+       // #given - boulder state without session-append-test, Atlas caller
        const sessionID = "session-append-test"
-       setupMessageStorage(sessionID, "atlas")
+       setupMessageStorage(sessionID, "Atlas")
       
       const planPath = join(TEST_DIR, "test-plan.md")
       writeFileSync(planPath, "# Plan\n- [ ] Task 1")
@@ -259,9 +259,9 @@ describe("atlas hook", () => {
     })
 
      test("should not duplicate existing session ID", async () => {
-       // #given - boulder state already has session-dup-test, atlas caller
+       // #given - boulder state already has session-dup-test, Atlas caller
        const sessionID = "session-dup-test"
-       setupMessageStorage(sessionID, "atlas")
+       setupMessageStorage(sessionID, "Atlas")
       
       const planPath = join(TEST_DIR, "test-plan.md")
       writeFileSync(planPath, "# Plan\n- [ ] Task 1")
@@ -296,9 +296,9 @@ describe("atlas hook", () => {
     })
 
      test("should include boulder.json path and notepad path in transformed output", async () => {
-       // #given - boulder state, atlas caller
+       // #given - boulder state, Atlas caller
        const sessionID = "session-path-test"
-       setupMessageStorage(sessionID, "atlas")
+       setupMessageStorage(sessionID, "Atlas")
       
       const planPath = join(TEST_DIR, "my-feature.md")
       writeFileSync(planPath, "# Plan\n- [ ] Task 1\n- [ ] Task 2\n- [x] Task 3")
@@ -333,9 +333,9 @@ describe("atlas hook", () => {
     })
 
      test("should include resume and checkbox instructions in reminder", async () => {
-       // #given - boulder state, atlas caller
+       // #given - boulder state, Atlas caller
        const sessionID = "session-resume-test"
-       setupMessageStorage(sessionID, "atlas")
+       setupMessageStorage(sessionID, "Atlas")
       
       const planPath = join(TEST_DIR, "test-plan.md")
       writeFileSync(planPath, "# Plan\n- [ ] Task 1")
@@ -373,7 +373,7 @@ describe("atlas hook", () => {
       const ORCHESTRATOR_SESSION = "orchestrator-write-test"
 
        beforeEach(() => {
-         setupMessageStorage(ORCHESTRATOR_SESSION, "atlas")
+         setupMessageStorage(ORCHESTRATOR_SESSION, "Atlas")
        })
 
       afterEach(() => {
@@ -601,7 +601,7 @@ describe("atlas hook", () => {
          getMainSessionID: () => MAIN_SESSION_ID,
          subagentSessions: new Set<string>(),
        }))
-       setupMessageStorage(MAIN_SESSION_ID, "atlas")
+       setupMessageStorage(MAIN_SESSION_ID, "Atlas")
      })
 
     afterEach(() => {
@@ -830,8 +830,8 @@ describe("atlas hook", () => {
       expect(callArgs.body.parts[0].text).toContain("2 remaining")
     })
 
-     test("should not inject when last agent is not atlas", async () => {
-       // #given - boulder state with incomplete plan, but last agent is NOT atlas
+     test("should not inject when last agent is not Atlas", async () => {
+       // #given - boulder state with incomplete plan, but last agent is NOT Atlas
        const planPath = join(TEST_DIR, "test-plan.md")
        writeFileSync(planPath, "# Plan\n- [ ] Task 1\n- [ ] Task 2")
 
@@ -843,7 +843,7 @@ describe("atlas hook", () => {
        }
        writeBoulderState(TEST_DIR, state)
 
-       // #given - last agent is NOT atlas
+       // #given - last agent is NOT Atlas
        cleanupMessageStorage(MAIN_SESSION_ID)
        setupMessageStorage(MAIN_SESSION_ID, "Sisyphus")
 
@@ -858,7 +858,7 @@ describe("atlas hook", () => {
          },
        })
 
-       // #then - should NOT call prompt because agent is not atlas
+       // #then - should NOT call prompt because agent is not Atlas
        expect(mockInput._promptMock).not.toHaveBeenCalled()
      })
 
diff --git a/src/hooks/atlas/index.ts b/src/hooks/atlas/index.ts
index 6a2f9638f..f35d70c21 100644
--- a/src/hooks/atlas/index.ts
+++ b/src/hooks/atlas/index.ts
@@ -111,7 +111,7 @@ const ORCHESTRATOR_DELEGATION_REQUIRED = `
 
 **STOP. YOU ARE VIOLATING ORCHESTRATOR PROTOCOL.**
 
-You (atlas) are attempting to directly modify a file outside \`.sisyphus/\`.
+You (Atlas) are attempting to directly modify a file outside \`.sisyphus/\`.
 
 **Path attempted:** $FILE_PATH
 
@@ -397,7 +397,7 @@ function isCallerOrchestrator(sessionID?: string): boolean {
    const messageDir = getMessageDir(sessionID)
    if (!messageDir) return false
    const nearest = findNearestMessageWithFields(messageDir)
-   return nearest?.agent === "atlas"
+   return nearest?.agent === "Atlas"
  }
 
 interface SessionState {
@@ -496,7 +496,7 @@ export function createAtlasHook(
        await ctx.client.session.prompt({
          path: { id: sessionID },
          body: {
-           agent: "atlas",
+            agent: "Atlas",
            ...(model !== undefined ? { model } : {}),
            parts: [{ type: "text", text: prompt }],
          },
@@ -569,7 +569,7 @@ export function createAtlasHook(
         }
 
         if (!isCallerOrchestrator(sessionID)) {
-          log(`[${HOOK_NAME}] Skipped: last agent is not atlas`, { sessionID })
+          log(`[${HOOK_NAME}] Skipped: last agent is not Atlas`, { sessionID })
           return
         }
 
diff --git a/src/hooks/start-work/index.test.ts b/src/hooks/start-work/index.test.ts
index c13b5193f..df4a20631 100644
--- a/src/hooks/start-work/index.test.ts
+++ b/src/hooks/start-work/index.test.ts
@@ -379,7 +379,7 @@ describe("start-work hook", () => {
   })
 
   describe("session agent management", () => {
-    test("should update session agent to atlas when start-work command is triggered", async () => {
+    test("should update session agent to Atlas when start-work command is triggered", async () => {
       // #given
       const updateSpy = spyOn(sessionState, "updateSessionAgent")
       
@@ -395,7 +395,7 @@ describe("start-work hook", () => {
       )
 
       // #then
-      expect(updateSpy).toHaveBeenCalledWith("ses-prometheus-to-sisyphus", "atlas")
+      expect(updateSpy).toHaveBeenCalledWith("ses-prometheus-to-sisyphus", "Atlas")
       updateSpy.mockRestore()
     })
   })
diff --git a/src/hooks/start-work/index.ts b/src/hooks/start-work/index.ts
index 4f3d528b2..dc03d3c71 100644
--- a/src/hooks/start-work/index.ts
+++ b/src/hooks/start-work/index.ts
@@ -71,7 +71,7 @@ export function createStartWorkHook(ctx: PluginInput) {
         sessionID: input.sessionID,
       })
 
-      updateSessionAgent(input.sessionID, "atlas")
+      updateSessionAgent(input.sessionID, "Atlas")
 
       const existingState = readBoulderState(ctx.directory)
       const sessionId = input.sessionID
diff --git a/src/plugin-handlers/config-handler.ts b/src/plugin-handlers/config-handler.ts
index 948df8c39..3ba18add2 100644
--- a/src/plugin-handlers/config-handler.ts
+++ b/src/plugin-handlers/config-handler.ts
@@ -160,7 +160,7 @@ export function createConfigHandler(deps: ConfigHandlerDeps) {
       explore?: { tools?: Record<string, unknown> };
       librarian?: { tools?: Record<string, unknown> };
       "multimodal-looker"?: { tools?: Record<string, unknown> };
-      atlas?: { tools?: Record<string, unknown> };
+      Atlas?: { tools?: Record<string, unknown> };
       Sisyphus?: { tools?: Record<string, unknown> };
     };
     const configAgent = config.agent as AgentConfig | undefined;
@@ -319,8 +319,8 @@ export function createConfigHandler(deps: ConfigHandlerDeps) {
       const agent = agentResult["multimodal-looker"] as AgentWithPermission;
       agent.permission = { ...agent.permission, task: "deny", look_at: "deny" };
     }
-    if (agentResult["atlas"]) {
-      const agent = agentResult["atlas"] as AgentWithPermission;
+    if (agentResult["Atlas"]) {
+      const agent = agentResult["Atlas"] as AgentWithPermission;
       agent.permission = { ...agent.permission, task: "deny", call_omo_agent: "deny", delegate_task: "allow" };
     }
     if (agentResult.Sisyphus) {
diff --git a/src/shared/migration.test.ts b/src/shared/migration.test.ts
index 0bcbbde86..84e563ae4 100644
--- a/src/shared/migration.test.ts
+++ b/src/shared/migration.test.ts
@@ -64,7 +64,7 @@ describe("migrateAgentNames", () => {
     // #then: Case-insensitive lookup should migrate correctly
     expect(migrated["Sisyphus"]).toEqual({ model: "test" })
     expect(migrated["Prometheus (Planner)"]).toEqual({ prompt: "test" })
-    expect(migrated["atlas"]).toEqual({ model: "openai/gpt-5.2" })
+    expect(migrated["Atlas"]).toEqual({ model: "openai/gpt-5.2" })
   })
 
   test("passes through unknown agent names unchanged", () => {
@@ -81,7 +81,7 @@ describe("migrateAgentNames", () => {
     expect(migrated["custom-agent"]).toEqual({ model: "custom/model" })
   })
 
-  test("migrates orchestrator-sisyphus to atlas", () => {
+  test("migrates orchestrator-sisyphus to Atlas", () => {
     // #given: Config with legacy orchestrator-sisyphus agent name
     const agents = {
       "orchestrator-sisyphus": { model: "anthropic/claude-opus-4-5" },
@@ -90,11 +90,26 @@ describe("migrateAgentNames", () => {
     // #when: Migrate agent names
     const { migrated, changed } = migrateAgentNames(agents)
 
-    // #then: orchestrator-sisyphus should be migrated to atlas
+    // #then: orchestrator-sisyphus should be migrated to Atlas
     expect(changed).toBe(true)
-    expect(migrated["atlas"]).toEqual({ model: "anthropic/claude-opus-4-5" })
+    expect(migrated["Atlas"]).toEqual({ model: "anthropic/claude-opus-4-5" })
     expect(migrated["orchestrator-sisyphus"]).toBeUndefined()
   })
+
+  test("migrates lowercase atlas to Atlas", () => {
+    // #given: Config with lowercase atlas agent name
+    const agents = {
+      atlas: { model: "anthropic/claude-opus-4-5" },
+    }
+
+    // #when: Migrate agent names
+    const { migrated, changed } = migrateAgentNames(agents)
+
+    // #then: lowercase atlas should be migrated to Atlas
+    expect(changed).toBe(true)
+    expect(migrated["Atlas"]).toEqual({ model: "anthropic/claude-opus-4-5" })
+    expect(migrated["atlas"]).toBeUndefined()
+  })
 })
 
 describe("migrateHookNames", () => {
diff --git a/src/shared/migration.ts b/src/shared/migration.ts
index 4f407b9da..3f9b005c8 100644
--- a/src/shared/migration.ts
+++ b/src/shared/migration.ts
@@ -18,7 +18,8 @@ export const AGENT_NAME_MAP: Record<string, string> = {
   librarian: "librarian",
   explore: "explore",
   "multimodal-looker": "multimodal-looker",
-  "orchestrator-sisyphus": "atlas",
+  "orchestrator-sisyphus": "Atlas",
+  atlas: "Atlas",
 }
 
 export const BUILTIN_AGENT_NAMES = new Set([
@@ -30,7 +31,7 @@ export const BUILTIN_AGENT_NAMES = new Set([
   "Metis (Plan Consultant)",
   "Momus (Plan Reviewer)",
   "Prometheus (Planner)",
-  "atlas",
+  "Atlas",
   "build",
 ])