diff --git a/src/cli/run/message-part-delta.test.ts b/src/cli/run/message-part-delta.test.ts
index 179366a24..6d7fefa6e 100644
--- a/src/cli/run/message-part-delta.test.ts
+++ b/src/cli/run/message-part-delta.test.ts
@@ -89,7 +89,7 @@ describe("message.part.delta handling", () => {
     //#given
     const ctx = createMockContext("ses_main")
     const state = createEventState()
-    state.agentColorsByName["Sisyphus (Ultraworker)"] = "#00CED1"
+    state.agentColorsByName["Sisyphus - Ultraworker"] = "#00CED1"
     const stdoutSpy = spyOn(process.stdout, "write").mockImplementation(() => true)
     const payload: EventPayload = {
       type: "message.updated",
@@ -97,7 +97,7 @@ describe("message.part.delta handling", () => {
         info: {
           sessionID: "ses_main",
           role: "assistant",
-          agent: "Sisyphus (Ultraworker)",
+          agent: "Sisyphus - Ultraworker",
           modelID: "claude-opus-4-6",
           variant: "max",
         },
@@ -115,7 +115,7 @@ describe("message.part.delta handling", () => {
     expect(rendered).toContain("\u001b[38;2;0;206;209m")
     expect(rendered).toContain("claude-opus-4-6 (max)")
     expect(rendered).toContain("└─")
-    expect(rendered).toContain("Sisyphus (Ultraworker)")
+    expect(rendered).toContain("Sisyphus - Ultraworker")
     stdoutSpy.mockRestore()
   })
 
@@ -128,7 +128,7 @@ describe("message.part.delta handling", () => {
       {
         type: "message.updated",
         properties: {
-          info: { sessionID: "ses_main", role: "assistant", agent: "Sisyphus (Ultraworker)", modelID: "claude-opus-4-6" },
+          info: { sessionID: "ses_main", role: "assistant", agent: "Sisyphus - Ultraworker", modelID: "claude-opus-4-6" },
         },
       },
       {
@@ -187,7 +187,7 @@ describe("message.part.delta handling", () => {
       {
         type: "message.updated",
         properties: {
-          info: { sessionID: "ses_main", role: "assistant", agent: "Sisyphus (Ultraworker)", modelID: "claude-opus-4-6" },
+          info: { sessionID: "ses_main", role: "assistant", agent: "Sisyphus - Ultraworker", modelID: "claude-opus-4-6" },
         },
       },
       {
@@ -242,7 +242,7 @@ describe("message.part.delta handling", () => {
       {
         type: "message.updated",
         properties: {
-          info: { id: "msg_assistant", sessionID: "ses_main", role: "assistant", agent: "Sisyphus (Ultraworker)", modelID: "claude-opus-4-6" },
+          info: { id: "msg_assistant", sessionID: "ses_main", role: "assistant", agent: "Sisyphus - Ultraworker", modelID: "claude-opus-4-6" },
         },
       },
       {
@@ -309,7 +309,7 @@ describe("message.part.delta handling", () => {
       {
         type: "message.updated",
         properties: {
-          info: { id: "msg_assistant", sessionID: "ses_main", role: "assistant", agent: "Sisyphus (Ultraworker)", modelID: "claude-opus-4-6" },
+          info: { id: "msg_assistant", sessionID: "ses_main", role: "assistant", agent: "Sisyphus - Ultraworker", modelID: "claude-opus-4-6" },
         },
       },
       {
@@ -353,7 +353,7 @@ describe("message.part.delta handling", () => {
       {
         type: "message.updated",
         properties: {
-          info: { id: "msg_assistant", sessionID: "ses_main", role: "assistant", agent: "Sisyphus (Ultraworker)", modelID: "claude-opus-4-6", variant: "max" },
+          info: { id: "msg_assistant", sessionID: "ses_main", role: "assistant", agent: "Sisyphus - Ultraworker", modelID: "claude-opus-4-6", variant: "max" },
         },
       },
       {
@@ -388,7 +388,7 @@ describe("message.part.delta handling", () => {
       {
         type: "message.updated",
         properties: {
-          info: { id: "msg_user", sessionID: "ses_main", role: "user", agent: "Sisyphus (Ultraworker)", modelID: "claude-opus-4-6" },
+          info: { id: "msg_user", sessionID: "ses_main", role: "user", agent: "Sisyphus - Ultraworker", modelID: "claude-opus-4-6" },
         },
       },
       {
@@ -410,7 +410,7 @@ describe("message.part.delta handling", () => {
       {
         type: "message.updated",
         properties: {
-          info: { id: "msg_assistant", sessionID: "ses_main", role: "assistant", agent: "Sisyphus (Ultraworker)", modelID: "claude-opus-4-6" },
+          info: { id: "msg_assistant", sessionID: "ses_main", role: "assistant", agent: "Sisyphus - Ultraworker", modelID: "claude-opus-4-6" },
         },
       },
       {
diff --git a/src/cli/run/runner.test.ts b/src/cli/run/runner.test.ts
index 19b7079a3..e0eb7ec3d 100644
--- a/src/cli/run/runner.test.ts
+++ b/src/cli/run/runner.test.ts
@@ -31,7 +31,7 @@ describe("resolveRunAgent", () => {
     )
 
     // then
-    expect(agent).toBe("Hephaestus (Deep Agent)")
+    expect(agent).toBe("Hephaestus - Deep Agent")
   })
 
   it("uses env agent over config", () => {
@@ -43,7 +43,7 @@ describe("resolveRunAgent", () => {
     const agent = resolveRunAgent({ message: "test" }, config, env)
 
     // then
-    expect(agent).toBe("Atlas (Plan Executor)")
+    expect(agent).toBe("Atlas - Plan Executor")
   })
 
   it("uses config agent over default", () => {
@@ -54,7 +54,7 @@ describe("resolveRunAgent", () => {
     const agent = resolveRunAgent({ message: "test" }, config, {})
 
     // then
-    expect(agent).toBe("Prometheus (Plan Builder)")
+    expect(agent).toBe("Prometheus - Plan Builder")
   })
 
   it("falls back to sisyphus when none set", () => {
@@ -65,7 +65,7 @@ describe("resolveRunAgent", () => {
     const agent = resolveRunAgent({ message: "test" }, config, {})
 
     // then
-    expect(agent).toBe("Sisyphus (Ultraworker)")
+    expect(agent).toBe("Sisyphus - Ultraworker")
   })
 
   it("skips disabled sisyphus for next available core agent", () => {
@@ -76,18 +76,18 @@ describe("resolveRunAgent", () => {
     const agent = resolveRunAgent({ message: "test" }, config, {})
 
     // then
-    expect(agent).toBe("Hephaestus (Deep Agent)")
+    expect(agent).toBe("Hephaestus - Deep Agent")
   })
 
   it("maps display-name style default_run_agent values to canonical display names", () => {
     // given
-    const config = createConfig({ default_run_agent: "Sisyphus (Ultraworker)" })
+    const config = createConfig({ default_run_agent: "Sisyphus - Ultraworker" })
 
     // when
     const agent = resolveRunAgent({ message: "test" }, config, {})
 
     // then
-    expect(agent).toBe("Sisyphus (Ultraworker)")
+    expect(agent).toBe("Sisyphus - Ultraworker")
   })
 })
 
diff --git a/src/features/claude-code-session-state/state.test.ts b/src/features/claude-code-session-state/state.test.ts
index 3f860b060..89a755bdb 100644
--- a/src/features/claude-code-session-state/state.test.ts
+++ b/src/features/claude-code-session-state/state.test.ts
@@ -40,13 +40,13 @@ describe("claude-code-session-state", () => {
     test("should strip zero-width ordering prefixes before storing agent for session", () => {
       // given
       const sessionID = "test-session-prefixed"
-      const agent = "\u200B\u200B\u200BPrometheus (Plan Builder)"
+      const agent = "\u200B\u200B\u200BPrometheus - Plan Builder"
 
       // when
       setSessionAgent(sessionID, agent)
 
       // then
-      expect(getSessionAgent(sessionID)).toBe("Prometheus (Plan Builder)")
+      expect(getSessionAgent(sessionID)).toBe("Prometheus - Plan Builder")
     })
 
     test("should NOT overwrite existing agent (first-write wins)", () => {
@@ -88,10 +88,10 @@ describe("claude-code-session-state", () => {
       setSessionAgent(sessionID, "sisyphus")
 
       // when
-      updateSessionAgent(sessionID, "\u200B\u200BHephaestus (Deep Agent)")
+      updateSessionAgent(sessionID, "\u200B\u200BHephaestus - Deep Agent")
 
       // then
-      expect(getSessionAgent(sessionID)).toBe("Hephaestus (Deep Agent)")
+      expect(getSessionAgent(sessionID)).toBe("Hephaestus - Deep Agent")
     })
   })
 
@@ -133,21 +133,21 @@ describe("claude-code-session-state", () => {
   describe("agent registration", () => {
     test("should register config-key lookup when given a display name", () => {
       // given
-      registerAgentName("Atlas (Plan Executor)")
+      registerAgentName("Atlas - Plan Executor")
 
       // when / then
       expect(isAgentRegistered("atlas")).toBe(true)
-      expect(isAgentRegistered("Atlas (Plan Executor)")).toBe(true)
+      expect(isAgentRegistered("Atlas - Plan Executor")).toBe(true)
     })
 
     describe("#given atlas display name with zero-width prefix", () => {
       describe("#when checking registration without the zero-width prefix", () => {
         test("#then it treats the display name as registered", () => {
           // given
-          registerAgentName("\u200BAtlas (Plan Executor)")
+          registerAgentName("\u200BAtlas - Plan Executor")
 
           // when
-          const isRegistered = isAgentRegistered("Atlas (Plan Executor)")
+          const isRegistered = isAgentRegistered("Atlas - Plan Executor")
 
           // then
           expect(isRegistered).toBe(true)
diff --git a/src/hooks/atlas/index.test.ts b/src/hooks/atlas/index.test.ts
index f2f2fd68f..0f9e7d605 100644
--- a/src/hooks/atlas/index.test.ts
+++ b/src/hooks/atlas/index.test.ts
@@ -1817,10 +1817,10 @@ session_id: ses_untrusted_999
         started_at: "2026-01-02T10:00:00Z",
         session_ids: [MAIN_SESSION_ID],
         plan_name: "test-plan",
-        agent: "Atlas (Plan Executor)",
+        agent: "Atlas - Plan Executor",
       }
       writeBoulderState(TEST_DIR, state)
-      registerAgentName("Atlas (Plan Executor)")
+      registerAgentName("Atlas - Plan Executor")
 
       const mockInput = createMockPluginInput()
       const hook = createAtlasHook(mockInput)
@@ -1836,7 +1836,7 @@ session_id: ses_untrusted_999
       // then
       expect(mockInput._promptMock).toHaveBeenCalled()
       const callArgs = mockInput._promptMock.mock.calls[0][0]
-      expect(callArgs.body.agent).toBe("Atlas (Plan Executor)")
+      expect(callArgs.body.agent).toBe("Atlas - Plan Executor")
       expect(callArgs.body.agent).not.toBe("atlas")
     })
 
diff --git a/src/hooks/model-fallback/hook.test.ts b/src/hooks/model-fallback/hook.test.ts
index 8c59db5f5..c16cbdbb5 100644
--- a/src/hooks/model-fallback/hook.test.ts
+++ b/src/hooks/model-fallback/hook.test.ts
@@ -94,7 +94,7 @@ describe("model fallback hook", () => {
 
     const set = setPendingModelFallback(
       "ses_model_fallback_main",
-      "Sisyphus (Ultraworker)",
+      "Sisyphus - Ultraworker",
       "anthropic",
       "claude-opus-4-6-thinking",
     )
@@ -132,7 +132,7 @@ describe("model fallback hook", () => {
     const sessionID = "ses_model_fallback_main"
 
     expect(
-      setPendingModelFallback(sessionID, "Sisyphus (Ultraworker)", "anthropic", "claude-opus-4-6-thinking"),
+      setPendingModelFallback(sessionID, "Sisyphus - Ultraworker", "anthropic", "claude-opus-4-6-thinking"),
     ).toBe(true)
 
     const firstOutput = {
@@ -154,7 +154,7 @@ describe("model fallback hook", () => {
 
     //#when - second error re-arms fallback and should advance to next entry
     expect(
-      setPendingModelFallback(sessionID, "Sisyphus (Ultraworker)", "anthropic", "claude-opus-4-6"),
+      setPendingModelFallback(sessionID, "Sisyphus - Ultraworker", "anthropic", "claude-opus-4-6"),
     ).toBe(true)
 
     const secondOutput = {
@@ -181,13 +181,13 @@ describe("model fallback hook", () => {
     //#when
     const firstSet = setPendingModelFallback(
       sessionID,
-      "Sisyphus (Ultraworker)",
+      "Sisyphus - Ultraworker",
       "anthropic",
       "claude-opus-4-6-thinking",
     )
     const secondSet = setPendingModelFallback(
       sessionID,
-      "Sisyphus (Ultraworker)",
+      "Sisyphus - Ultraworker",
       "anthropic",
       "claude-opus-4-6-thinking",
     )
@@ -218,7 +218,7 @@ describe("model fallback hook", () => {
     expect(
       setPendingModelFallback(
         sessionID,
-        "Sisyphus (Ultraworker)",
+        "Sisyphus - Ultraworker",
         "anthropic",
         "claude-opus-4-6",
       ),
@@ -262,7 +262,7 @@ describe("model fallback hook", () => {
     expect(
       setPendingModelFallback(
         sessionID,
-        "Sisyphus (Ultraworker)",
+        "Sisyphus - Ultraworker",
         "quotio",
         "claude-opus-4-6",
       ),
@@ -308,7 +308,7 @@ describe("model fallback hook", () => {
     expect(
       setPendingModelFallback(
         sessionID,
-        "Sisyphus (Ultraworker)",
+        "Sisyphus - Ultraworker",
         "provider-x",
         "current-model",
       ),
@@ -348,7 +348,7 @@ describe("model fallback hook", () => {
 
     const set = setPendingModelFallback(
       "ses_model_fallback_toast",
-      "Sisyphus (Ultraworker)",
+      "Sisyphus - Ultraworker",
       "anthropic",
       "claude-opus-4-6-thinking",
     )
@@ -389,7 +389,7 @@ describe("model fallback hook", () => {
 
     const set = setPendingModelFallback(
       sessionID,
-      "Atlas (Plan Executor)",
+      "Atlas - Plan Executor",
       "github-copilot",
       "claude-sonnet-4-5",
     )
diff --git a/src/hooks/no-hephaestus-non-gpt/hook.ts b/src/hooks/no-hephaestus-non-gpt/hook.ts
index e621c6d01..afce7ba9c 100644
--- a/src/hooks/no-hephaestus-non-gpt/hook.ts
+++ b/src/hooks/no-hephaestus-non-gpt/hook.ts
@@ -54,11 +54,11 @@ export function createNoHephaestusNonGptHook(
         if (allowNonGptModel) {
           return
         }
-        input.agent = SISYPHUS_DISPLAY
+        input.agent = "sisyphus"
         if (output?.message) {
-          output.message.agent = SISYPHUS_DISPLAY
+          output.message.agent = "sisyphus"
         }
-        updateSessionAgent(input.sessionID, SISYPHUS_DISPLAY)
+        updateSessionAgent(input.sessionID, "sisyphus")
       }
     },
   }
diff --git a/src/hooks/no-hephaestus-non-gpt/index.test.ts b/src/hooks/no-hephaestus-non-gpt/index.test.ts
index 3440cccc8..7686bdbf1 100644
--- a/src/hooks/no-hephaestus-non-gpt/index.test.ts
+++ b/src/hooks/no-hephaestus-non-gpt/index.test.ts
@@ -40,8 +40,8 @@ describe("no-hephaestus-non-gpt hook", () => {
 
     // then - toast is shown and agent is switched to sisyphus
     expect(showToast).toHaveBeenCalledTimes(2)
-    expect(output1.message.agent).toBe(SISYPHUS_DISPLAY)
-    expect(output2.message.agent).toBe(SISYPHUS_DISPLAY)
+    expect(output1.message.agent).toBe("sisyphus")
+    expect(output2.message.agent).toBe("sisyphus")
     expect(showToast.mock.calls[0]?.[0]).toMatchObject({
       body: {
         title: "NEVER Use Hephaestus with Non-GPT",
@@ -141,6 +141,6 @@ describe("no-hephaestus-non-gpt hook", () => {
 
     // then - toast shown via session-agent fallback, switched to sisyphus
     expect(showToast).toHaveBeenCalledTimes(1)
-    expect(output.message.agent).toBe(SISYPHUS_DISPLAY)
+    expect(output.message.agent).toBe("sisyphus")
   })
 })
diff --git a/src/hooks/no-sisyphus-gpt/hook.ts b/src/hooks/no-sisyphus-gpt/hook.ts
index a4e6c77da..65ab8d113 100644
--- a/src/hooks/no-sisyphus-gpt/hook.ts
+++ b/src/hooks/no-sisyphus-gpt/hook.ts
@@ -43,11 +43,11 @@ export function createNoSisyphusGptHook(ctx: PluginInput) {
 
       if (agentKey === "sisyphus" && modelID && isGptModel(modelID) && !isGpt5_4Model(modelID)) {
         showToast(ctx, input.sessionID)
-        input.agent = HEPHAESTUS_DISPLAY
+        input.agent = "hephaestus"
         if (output?.message) {
-          output.message.agent = HEPHAESTUS_DISPLAY
+          output.message.agent = "hephaestus"
         }
-        updateSessionAgent(input.sessionID, HEPHAESTUS_DISPLAY)
+        updateSessionAgent(input.sessionID, "hephaestus")
       }
     },
   }
diff --git a/src/hooks/no-sisyphus-gpt/index.test.ts b/src/hooks/no-sisyphus-gpt/index.test.ts
index c5fef658d..908a01351 100644
--- a/src/hooks/no-sisyphus-gpt/index.test.ts
+++ b/src/hooks/no-sisyphus-gpt/index.test.ts
@@ -38,8 +38,8 @@ describe("no-sisyphus-gpt hook", () => {
 
     // then - toast is shown for every message
     expect(showToast).toHaveBeenCalledTimes(2)
-    expect(output1.message.agent).toBe(HEPHAESTUS_DISPLAY)
-    expect(output2.message.agent).toBe(HEPHAESTUS_DISPLAY)
+    expect(output1.message.agent).toBe("hephaestus")
+    expect(output2.message.agent).toBe("hephaestus")
     expect(showToast.mock.calls[0]?.[0]).toMatchObject({
       body: {
         title: "NEVER Use Sisyphus with GPT",
@@ -131,6 +131,6 @@ describe("no-sisyphus-gpt hook", () => {
 
     // then - toast shown via session-agent fallback
     expect(showToast).toHaveBeenCalledTimes(1)
-    expect(output.message.agent).toBe(HEPHAESTUS_DISPLAY)
+    expect(output.message.agent).toBe("hephaestus")
   })
 })
diff --git a/src/hooks/prometheus-md-only/index.test.ts b/src/hooks/prometheus-md-only/index.test.ts
index 5ff8d0ece..f51ac88e7 100644
--- a/src/hooks/prometheus-md-only/index.test.ts
+++ b/src/hooks/prometheus-md-only/index.test.ts
@@ -94,7 +94,7 @@ describe("prometheus-md-only", () => {
 
     test("should enforce md-only restriction for Prometheus display name Plan Builder", async () => {
       //#given
-      setupMessageStorage(TEST_SESSION_ID, "Prometheus (Plan Builder)")
+      setupMessageStorage(TEST_SESSION_ID, "Prometheus - Plan Builder")
       const hook = createPrometheusMdOnlyHook(createMockPluginInput())
       const input = {
         tool: "Write",
diff --git a/src/hooks/runtime-fallback/auto-retry.ts b/src/hooks/runtime-fallback/auto-retry.ts
index fa8d1154a..de946af5b 100644
--- a/src/hooks/runtime-fallback/auto-retry.ts
+++ b/src/hooks/runtime-fallback/auto-retry.ts
@@ -133,14 +133,14 @@ export function createAutoRetryHelpers(deps: HookDeps) {
         })
 
         const retryAgent = resolvedAgent ?? getSessionAgent(sessionID)
-        const retryAgentDisplayName = retryAgent ? getAgentDisplayName(retryAgent) : undefined
         sessionAwaitingFallbackResult.add(sessionID)
         scheduleSessionFallbackTimeout(sessionID, retryAgent)
 
         await ctx.client.session.promptAsync({
           path: { id: sessionID },
           body: {
-            ...(retryAgentDisplayName ? { agent: retryAgentDisplayName } : {}),
+            // Use config key to avoid HTTP header validation issues with display names
+            ...(retryAgent ? { agent: retryAgent } : {}),
             ...retryModelPayload,
             parts: retryParts,
           },
diff --git a/src/hooks/runtime-fallback/index.test.ts b/src/hooks/runtime-fallback/index.test.ts
index fce27febe..a1b52c96e 100644
--- a/src/hooks/runtime-fallback/index.test.ts
+++ b/src/hooks/runtime-fallback/index.test.ts
@@ -2458,7 +2458,7 @@ describe("runtime-fallback", () => {
 
       expect(promptCalls.length).toBe(1)
       const callBody = promptCalls[0]?.body as Record<string, unknown>
-      expect(callBody?.agent).toBe("Prometheus (Plan Builder)")
+      expect(callBody?.agent).toBe("prometheus")
       expect(callBody?.model).toEqual({ providerID: "github-copilot", modelID: "claude-opus-4.6" })
     })
   })
diff --git a/src/hooks/start-work/index.test.ts b/src/hooks/start-work/index.test.ts
index 874c7910f..9957b9608 100644
--- a/src/hooks/start-work/index.test.ts
+++ b/src/hooks/start-work/index.test.ts
@@ -453,7 +453,7 @@ You are starting a Sisyphus work session.
       )
 
       // then
-      expect(output.message.agent).toBe(getAgentListDisplayName("atlas"))
+      expect(output.message.agent).toBe("atlas")
     })
 
     test("should switch to Atlas even when current session is Sisyphus (regression: #3155)", async () => {
@@ -473,7 +473,7 @@ You are starting a Sisyphus work session.
       )
 
       // atlas is registered in beforeEach, so it must be selected
-      expect(output.message.agent).toBe(getAgentListDisplayName("atlas"))
+      expect(output.message.agent).toBe("atlas")
       expect(sessionState.getSessionAgent("ses-sisyphus-to-atlas")).toBe("atlas")
     })
 
@@ -496,7 +496,7 @@ You are starting a Sisyphus work session.
       )
 
       // then
-      expect(output.message.agent).toBe("Sisyphus (Ultraworker)")
+      expect(output.message.agent).toBe("sisyphus")
       expect(sessionState.getSessionAgent("ses-prometheus-to-sisyphus")).toBe("sisyphus")
     })
 
@@ -524,7 +524,7 @@ You are starting a Sisyphus work session.
       )
 
       // then
-      expect(output.message.agent).toBe("Sisyphus (Ultraworker)")
+      expect(output.message.agent).toBe("sisyphus")
       expect(sessionState.getSessionAgent("ses-prometheus-to-worker")).toBe("sisyphus")
       expect(readBoulderState(testDir)?.agent).toBe("sisyphus")
     })
@@ -559,7 +559,7 @@ You are starting a Sisyphus work session.
       )
 
       // then
-      expect(output.message.agent).toBe("Sisyphus (Ultraworker)")
+      expect(output.message.agent).toBe("sisyphus")
       expect(readBoulderState(testDir)?.agent).toBe("sisyphus")
     })
 
@@ -594,7 +594,7 @@ You are starting a Sisyphus work session.
       await atlasHook.handler({ event: { type: "session.idle", properties: { sessionID: "session-123" } } })
 
       // then
-      expect(output.message.agent).toBe(getAgentListDisplayName("atlas"))
+      expect(output.message.agent).toBe("atlas")
       expect(readBoulderState(testDir)?.session_ids).toContain("session-123")
       expect(readBoulderState(testDir)?.agent).toBe("atlas")
       expect(promptAsyncMock).toHaveBeenCalledTimes(1)
@@ -684,7 +684,7 @@ You are starting a Sisyphus work session.
         await firePendingTimers()
 
         // then
-        expect(output.message.agent).toBe(getAgentListDisplayName("atlas"))
+        expect(output.message.agent).toBe("atlas")
         expect(readBoulderState(testDir)?.session_ids).toContain("session-123")
         expect(readBoulderState(testDir)?.agent).toBe("atlas")
         expect(promptAsyncMock).toHaveBeenCalledTimes(1)
diff --git a/src/hooks/start-work/start-work-hook.ts b/src/hooks/start-work/start-work-hook.ts
index f916c2eae..357f9552a 100644
--- a/src/hooks/start-work/start-work-hook.ts
+++ b/src/hooks/start-work/start-work-hook.ts
@@ -85,12 +85,12 @@ export function createStartWorkHook(ctx: PluginInput) {
     const activeAgent = isAgentRegistered("atlas")
       ? "atlas"
       : "sisyphus"
-    const activeAgentDisplayName = activeAgent === "atlas"
-      ? getAgentListDisplayName(activeAgent)
-      : getAgentDisplayName(activeAgent)
+    const activeAgentDisplayName = getAgentDisplayName(activeAgent)
     updateSessionAgent(input.sessionID, activeAgent)
     if (output.message) {
-      output.message["agent"] = activeAgentDisplayName
+      // Use config key for agent field to avoid HTTP header validation issues
+      // Display names like "Atlas (Plan Executor)" contain parens that are invalid in headers
+      output.message["agent"] = activeAgent
     }
 
     const existingState = readBoulderState(ctx.directory)
diff --git a/src/hooks/todo-continuation-enforcer/continuation-injection.test.ts b/src/hooks/todo-continuation-enforcer/continuation-injection.test.ts
index 8feac9863..b7015b517 100644
--- a/src/hooks/todo-continuation-enforcer/continuation-injection.test.ts
+++ b/src/hooks/todo-continuation-enforcer/continuation-injection.test.ts
@@ -33,7 +33,7 @@ describe("injectContinuation", () => {
       ctx: ctx as never,
       sessionID: "ses_display_name_agent",
       resolvedInfo: {
-        agent: "Sisyphus (Ultraworker)",
+        agent: "Sisyphus - Ultraworker",
         model: { providerID: "anthropic", modelID: "claude-sonnet-4-20250514" },
       },
       sessionStateStore: sessionStateStore as never,
diff --git a/src/plugin-handlers/agent-override-protection.ts b/src/plugin-handlers/agent-override-protection.ts
index 476937b8c..1394698a9 100644
--- a/src/plugin-handlers/agent-override-protection.ts
+++ b/src/plugin-handlers/agent-override-protection.ts
@@ -1,4 +1,5 @@
 const PARENTHETICAL_SUFFIX_PATTERN = /\s*(\([^)]*\)\s*)+$/u
+const DASH_SUFFIX_PATTERN = /\s+-\s+.+$/u
 const ZERO_WIDTH_CHARACTERS_PATTERN = /[\u200B\u200C\u200D\uFEFF]/g
 
 export function normalizeProtectedAgentName(agentName: string): string {
@@ -7,6 +8,7 @@ export function normalizeProtectedAgentName(agentName: string): string {
     .trim()
     .toLowerCase()
     .replace(PARENTHETICAL_SUFFIX_PATTERN, "")
+    .replace(DASH_SUFFIX_PATTERN, "")
     .replace(/[-_]/g, "")
     .trim()
 }
diff --git a/src/plugin-interface.test.ts b/src/plugin-interface.test.ts
index a3699668c..4dac3f7be 100644
--- a/src/plugin-interface.test.ts
+++ b/src/plugin-interface.test.ts
@@ -165,7 +165,7 @@ describe("createPluginInterface - command.execute.before", () => {
     )
 
     // then
-    expect(output.message.agent).toBe(getAgentListDisplayName("atlas"))
+    expect(output.message.agent).toBe("atlas")
     expect(getSessionAgent("ses-command-atlas")).toBe("atlas")
     expect(readBoulderState(testDir)?.agent).toBe("atlas")
   })
diff --git a/src/plugin/chat-message.test.ts b/src/plugin/chat-message.test.ts
index 11b4b6a48..e7128140b 100644
--- a/src/plugin/chat-message.test.ts
+++ b/src/plugin/chat-message.test.ts
@@ -87,7 +87,7 @@ describe("createChatMessageHandler - /start-work integration", () => {
     await handler(input, output)
 
     // then
-    expect(output.message["agent"]).toBe("Sisyphus (Ultraworker)")
+    expect(output.message["agent"]).toBe("sisyphus")
     expect(output.parts[0].text).toContain("<auto-slash-command>")
     expect(output.parts[0].text).toContain("Auto-Selected Plan")
     expect(output.parts[0].text).toContain("boulder.json has been created")
@@ -397,7 +397,7 @@ describe("createChatMessageHandler - TUI variant passthrough", () => {
     //#then
     expect(output.message["model"]).toBeUndefined()
     expect(getSessionModel("test-session")).toEqual({ providerID: "openai", modelID: "gpt-5.4" })
-    expect(getSessionAgent("test-session")).toBe("Prometheus (Plan Builder)")
+    expect(getSessionAgent("test-session")).toBe("Prometheus - Plan Builder")
   })
 
   test("respects a mid-conversation model switch instead of reusing the previous stored model", async () => {
diff --git a/src/plugin/event.model-fallback.test.ts b/src/plugin/event.model-fallback.test.ts
index 02c012070..481c5c419 100644
--- a/src/plugin/event.model-fallback.test.ts
+++ b/src/plugin/event.model-fallback.test.ts
@@ -92,8 +92,8 @@ describe("createEventHandler - model fallback", () => {
             parentID: "msg_user_1",
             modelID: "claude-opus-4-6-thinking",
             providerID: "anthropic",
-            mode: "Sisyphus (Ultraworker)",
-            agent: "Sisyphus (Ultraworker)",
+            mode: "Sisyphus - Ultraworker",
+            agent: "Sisyphus - Ultraworker",
             path: { cwd: "/tmp", root: "/tmp" },
             cost: 0,
             tokens: { input: 0, output: 0, reasoning: 0, cache: { read: 0, write: 0 } },
@@ -184,7 +184,7 @@ describe("createEventHandler - model fallback", () => {
             content: [],
             modelID: "claude-opus-4-6-thinking",
             providerID: "anthropic",
-            agent: "Sisyphus (Ultraworker)",
+            agent: "Sisyphus - Ultraworker",
             path: { cwd: "/tmp", root: "/tmp" },
           },
         },
@@ -246,7 +246,7 @@ describe("createEventHandler - model fallback", () => {
             role: "user",
             modelID: "claude-opus-4-6-thinking",
             providerID: "anthropic",
-            agent: "Sisyphus (Ultraworker)",
+            agent: "Sisyphus - Ultraworker",
           },
         },
       },
@@ -314,7 +314,7 @@ describe("createEventHandler - model fallback", () => {
             role: "user",
             modelID: "claude-opus-4-6",
             providerID: "quotio",
-            agent: "Sisyphus (Ultraworker)",
+            agent: "Sisyphus - Ultraworker",
           },
         },
       },
@@ -395,7 +395,7 @@ describe("createEventHandler - model fallback", () => {
             content: [],
             modelID: "claude-opus-4-6",
             providerID: "quotio",
-            agent: "Sisyphus (Ultraworker)",
+            agent: "Sisyphus - Ultraworker",
             path: { cwd: "/tmp", root: "/tmp" },
           },
         },
@@ -597,7 +597,7 @@ describe("createEventHandler - model fallback", () => {
             parentID: "msg_user_disabled_1",
             modelID: "claude-opus-4-6-thinking",
             providerID: "anthropic",
-            agent: "Sisyphus (Ultraworker)",
+            agent: "Sisyphus - Ultraworker",
             path: { cwd: "/tmp", root: "/tmp" },
             cost: 0,
             tokens: { input: 0, output: 0, reasoning: 0, cache: { read: 0, write: 0 } },
diff --git a/src/plugin/event.test.ts b/src/plugin/event.test.ts
index 28e2d7fb2..2fc453dc2 100644
--- a/src/plugin/event.test.ts
+++ b/src/plugin/event.test.ts
@@ -771,7 +771,7 @@ describe("createEventHandler - retry dedupe lifecycle", () => {
 						role: "user",
 						modelID: "claude-opus-4-6-thinking",
 						providerID: "anthropic",
-						agent: "Sisyphus (Ultraworker)",
+						agent: "Sisyphus - Ultraworker",
 					},
 				},
 			},
diff --git a/src/plugin/fallback.cliproxyapi-matrix.test.ts b/src/plugin/fallback.cliproxyapi-matrix.test.ts
index 8d8e3c6f4..30535a880 100644
--- a/src/plugin/fallback.cliproxyapi-matrix.test.ts
+++ b/src/plugin/fallback.cliproxyapi-matrix.test.ts
@@ -255,7 +255,7 @@ async function primeMainSession(
           content: [],
           modelID: PRIMARY_MODEL.modelID,
           providerID: PRIMARY_MODEL.providerID,
-          agent: "Sisyphus (Ultraworker)",
+          agent: "Sisyphus - Ultraworker",
           path: { cwd: "/tmp", root: "/tmp" },
         },
       },
@@ -337,7 +337,7 @@ async function triggerAssistantMessageError(
           model: PRIMARY_MODEL_STRING,
           modelID: PRIMARY_MODEL.modelID,
           providerID: PRIMARY_MODEL.providerID,
-          agent: "Sisyphus (Ultraworker)",
+          agent: "Sisyphus - Ultraworker",
           path: { cwd: "/tmp", root: "/tmp" },
           error: {
             statusCode: 529,
diff --git a/src/plugin/ultrawork-model-override.test.ts b/src/plugin/ultrawork-model-override.test.ts
index 9ceb42aae..0204f0cae 100644
--- a/src/plugin/ultrawork-model-override.test.ts
+++ b/src/plugin/ultrawork-model-override.test.ts
@@ -174,7 +174,7 @@ describe("resolveUltraworkOverride", () => {
     const output = createOutput("ulw do something")
 
     //#when
-    const result = resolveUltraworkOverride(config, "Sisyphus (Ultraworker)", output)
+    const result = resolveUltraworkOverride(config, "Sisyphus - Ultraworker", output)
 
     //#then
     expect(result).toEqual({ providerID: "anthropic", modelID: "claude-opus-4-6", variant: "max" })
@@ -408,7 +408,7 @@ describe("applyUltraworkModelOverrideOnMessage", () => {
     const tui = createMockTui()
 
     //#when
-    applyUltraworkModelOverrideOnMessage(config, "Sisyphus (Ultraworker)", output, tui)
+    applyUltraworkModelOverrideOnMessage(config, "Sisyphus - Ultraworker", output, tui)
 
     //#then
     expect(dbOverrideSpy).toHaveBeenCalledWith(
diff --git a/src/shared/agent-config-integration.test.ts b/src/shared/agent-config-integration.test.ts
index 25cd14a26..1afc2f033 100644
--- a/src/shared/agent-config-integration.test.ts
+++ b/src/shared/agent-config-integration.test.ts
@@ -92,12 +92,12 @@ describe("Agent Config Integration", () => {
       const displayNames = agents.map((agent) => getAgentDisplayName(agent))
 
       // then - display names are correct
-      expect(displayNames).toContain("Sisyphus (Ultraworker)")
-      expect(displayNames).toContain("Hephaestus (Deep Agent)")
-      expect(displayNames).toContain("Prometheus (Plan Builder)")
-      expect(displayNames).toContain("Atlas (Plan Executor)")
-      expect(displayNames).toContain("Metis (Plan Consultant)")
-      expect(displayNames).toContain("Momus (Plan Critic)")
+      expect(displayNames).toContain("Sisyphus - Ultraworker")
+      expect(displayNames).toContain("Hephaestus - Deep Agent")
+      expect(displayNames).toContain("Prometheus - Plan Builder")
+      expect(displayNames).toContain("Atlas - Plan Executor")
+      expect(displayNames).toContain("Metis - Plan Consultant")
+      expect(displayNames).toContain("Momus - Plan Critic")
       expect(displayNames).toContain("oracle")
       expect(displayNames).toContain("librarian")
       expect(displayNames).toContain("explore")
@@ -112,12 +112,12 @@ describe("Agent Config Integration", () => {
       const displayNames = keys.map((key) => getAgentDisplayName(key))
 
       // then - correct display names are returned
-      expect(displayNames[0]).toBe("Sisyphus (Ultraworker)")
-      expect(displayNames[1]).toBe("Atlas (Plan Executor)")
-      expect(displayNames[2]).toBe("Sisyphus (Ultraworker)")
-      expect(displayNames[3]).toBe("Atlas (Plan Executor)")
-      expect(displayNames[4]).toBe("Prometheus (Plan Builder)")
-      expect(displayNames[5]).toBe("Prometheus (Plan Builder)")
+      expect(displayNames[0]).toBe("Sisyphus - Ultraworker")
+      expect(displayNames[1]).toBe("Atlas - Plan Executor")
+      expect(displayNames[2]).toBe("Sisyphus - Ultraworker")
+      expect(displayNames[3]).toBe("Atlas - Plan Executor")
+      expect(displayNames[4]).toBe("Prometheus - Plan Builder")
+      expect(displayNames[5]).toBe("Prometheus - Plan Builder")
     })
 
     test("returns original key for unknown agents", () => {
@@ -189,8 +189,8 @@ describe("Agent Config Integration", () => {
       const prometheusDisplay = getAgentDisplayName("prometheus")
 
       // then - display names are correct
-      expect(sisyphusDisplay).toBe("Sisyphus (Ultraworker)")
-      expect(prometheusDisplay).toBe("Prometheus (Plan Builder)")
+      expect(sisyphusDisplay).toBe("Sisyphus - Ultraworker")
+      expect(prometheusDisplay).toBe("Prometheus - Plan Builder")
 
       // then - config values are preserved
       expect(result.migrated.sisyphus).toEqual({ model: "anthropic/claude-opus-4-6", temperature: 0.1 })
@@ -218,8 +218,8 @@ describe("Agent Config Integration", () => {
       const atlasDisplay = getAgentDisplayName("atlas")
 
       // then - display names are correct
-      expect(sisyphusDisplay).toBe("Sisyphus (Ultraworker)")
-      expect(atlasDisplay).toBe("Atlas (Plan Executor)")
+      expect(sisyphusDisplay).toBe("Sisyphus - Ultraworker")
+      expect(atlasDisplay).toBe("Atlas - Plan Executor")
     })
   })
 })
diff --git a/src/shared/agent-display-names.test.ts b/src/shared/agent-display-names.test.ts
index 538c16174..050e4cfde 100644
--- a/src/shared/agent-display-names.test.ts
+++ b/src/shared/agent-display-names.test.ts
@@ -9,8 +9,8 @@ describe("getAgentDisplayName", () => {
     // when getAgentDisplayName called
     const result = getAgentDisplayName(configKey)
 
-    // then returns "Sisyphus (Ultraworker)"
-    expect(result).toBe("Sisyphus (Ultraworker)")
+    // then returns "Sisyphus - Ultraworker"
+    expect(result).toBe("Sisyphus - Ultraworker")
   })
 
   it("returns display name for uppercase config key (old format - case-insensitive)", () => {
@@ -20,8 +20,8 @@ describe("getAgentDisplayName", () => {
     // when getAgentDisplayName called
     const result = getAgentDisplayName(configKey)
 
-    // then returns "Sisyphus (Ultraworker)" (case-insensitive lookup)
-    expect(result).toBe("Sisyphus (Ultraworker)")
+    // then returns "Sisyphus - Ultraworker" (case-insensitive lookup)
+    expect(result).toBe("Sisyphus - Ultraworker")
   })
 
   it("returns original key for unknown agents (fallback)", () => {
@@ -42,8 +42,8 @@ describe("getAgentDisplayName", () => {
     // when getAgentDisplayName called
     const result = getAgentDisplayName(configKey)
 
-     // then returns "Atlas (Plan Executor)"
-    expect(result).toBe("Atlas (Plan Executor)")
+     // then returns "Atlas - Plan Executor"
+    expect(result).toBe("Atlas - Plan Executor")
   })
 
   it("returns display name for prometheus", () => {
@@ -53,8 +53,8 @@ describe("getAgentDisplayName", () => {
     // when getAgentDisplayName called
     const result = getAgentDisplayName(configKey)
 
-    // then returns "Prometheus (Plan Builder)"
-    expect(result).toBe("Prometheus (Plan Builder)")
+    // then returns "Prometheus - Plan Builder"
+    expect(result).toBe("Prometheus - Plan Builder")
   })
 
   it("returns display name for sisyphus-junior", () => {
@@ -75,8 +75,8 @@ describe("getAgentDisplayName", () => {
     // when getAgentDisplayName called
     const result = getAgentDisplayName(configKey)
 
-    // then returns "Metis (Plan Consultant)"
-    expect(result).toBe("Metis (Plan Consultant)")
+    // then returns "Metis - Plan Consultant"
+    expect(result).toBe("Metis - Plan Consultant")
   })
 
   it("returns display name for momus", () => {
@@ -86,8 +86,8 @@ describe("getAgentDisplayName", () => {
     // when getAgentDisplayName called
     const result = getAgentDisplayName(configKey)
 
-     // then returns "Momus (Plan Critic)"
-    expect(result).toBe("Momus (Plan Critic)")
+     // then returns "Momus - Plan Critic"
+    expect(result).toBe("Momus - Plan Critic")
   })
 
   it("returns display name for oracle", () => {
@@ -137,17 +137,17 @@ describe("getAgentDisplayName", () => {
 
 describe("getAgentConfigKey", () => {
   it("resolves display name to config key", () => {
-    // given display name "Sisyphus (Ultraworker)"
+    // given display name "Sisyphus - Ultraworker"
     // when getAgentConfigKey called
     // then returns "sisyphus"
-    expect(getAgentConfigKey("Sisyphus (Ultraworker)")).toBe("sisyphus")
+    expect(getAgentConfigKey("Sisyphus - Ultraworker")).toBe("sisyphus")
   })
 
   it("resolves display name case-insensitively", () => {
     // given display name in different case
     // when getAgentConfigKey called
     // then returns "atlas"
-    expect(getAgentConfigKey("atlas (plan executor)")).toBe("atlas")
+    expect(getAgentConfigKey("atlas - plan executor")).toBe("atlas")
   })
 
   it("passes through lowercase config keys unchanged", () => {
@@ -167,11 +167,11 @@ describe("getAgentConfigKey", () => {
   it("resolves all core agent display names", () => {
     // given all core display names
     // when/then each resolves to its config key
-    expect(getAgentConfigKey("Hephaestus (Deep Agent)")).toBe("hephaestus")
-    expect(getAgentConfigKey("Prometheus (Plan Builder)")).toBe("prometheus")
-    expect(getAgentConfigKey("Atlas (Plan Executor)")).toBe("atlas")
-    expect(getAgentConfigKey("Metis (Plan Consultant)")).toBe("metis")
-    expect(getAgentConfigKey("Momus (Plan Critic)")).toBe("momus")
+    expect(getAgentConfigKey("Hephaestus - Deep Agent")).toBe("hephaestus")
+    expect(getAgentConfigKey("Prometheus - Plan Builder")).toBe("prometheus")
+    expect(getAgentConfigKey("Atlas - Plan Executor")).toBe("atlas")
+    expect(getAgentConfigKey("Metis - Plan Consultant")).toBe("metis")
+    expect(getAgentConfigKey("Momus - Plan Critic")).toBe("momus")
     expect(getAgentConfigKey("Sisyphus-Junior")).toBe("sisyphus-junior")
   })
 
@@ -182,10 +182,10 @@ describe("getAgentConfigKey", () => {
 
 describe("getAgentListDisplayName", () => {
   it("applies invisible stable-sort prefixes to the core agent list", () => {
-    expect(getAgentListDisplayName("sisyphus")).toBe("\u200BSisyphus (Ultraworker)")
-    expect(getAgentListDisplayName("hephaestus")).toBe("\u200B\u200BHephaestus (Deep Agent)")
-    expect(getAgentListDisplayName("prometheus")).toBe("\u200B\u200B\u200BPrometheus (Plan Builder)")
-    expect(getAgentListDisplayName("atlas")).toBe("\u200B\u200B\u200B\u200BAtlas (Plan Executor)")
+    expect(getAgentListDisplayName("sisyphus")).toBe("\u200BSisyphus - Ultraworker")
+    expect(getAgentListDisplayName("hephaestus")).toBe("\u200B\u200BHephaestus - Deep Agent")
+    expect(getAgentListDisplayName("prometheus")).toBe("\u200B\u200B\u200BPrometheus - Plan Builder")
+    expect(getAgentListDisplayName("atlas")).toBe("\u200B\u200B\u200B\u200BAtlas - Plan Executor")
   })
 
   it("keeps non-core agents unprefixed for list display", () => {
@@ -195,16 +195,16 @@ describe("getAgentListDisplayName", () => {
 
 describe("normalizeAgentForPrompt", () => {
   it("strips core UI ordering prefixes back to canonical display names", () => {
-    expect(normalizeAgentForPrompt(getAgentListDisplayName("sisyphus"))).toBe("Sisyphus (Ultraworker)")
-    expect(normalizeAgentForPrompt(getAgentListDisplayName("hephaestus"))).toBe("Hephaestus (Deep Agent)")
-    expect(normalizeAgentForPrompt(getAgentListDisplayName("prometheus"))).toBe("Prometheus (Plan Builder)")
-    expect(normalizeAgentForPrompt(getAgentListDisplayName("atlas"))).toBe("Atlas (Plan Executor)")
+    expect(normalizeAgentForPrompt(getAgentListDisplayName("sisyphus"))).toBe("Sisyphus - Ultraworker")
+    expect(normalizeAgentForPrompt(getAgentListDisplayName("hephaestus"))).toBe("Hephaestus - Deep Agent")
+    expect(normalizeAgentForPrompt(getAgentListDisplayName("prometheus"))).toBe("Prometheus - Plan Builder")
+    expect(normalizeAgentForPrompt(getAgentListDisplayName("atlas"))).toBe("Atlas - Plan Executor")
   })
 })
 
 describe("normalizeAgentForPromptKey", () => {
   it("converts built-in display names to config keys", () => {
-    expect(normalizeAgentForPromptKey("Sisyphus (Ultraworker)")).toBe("sisyphus")
+    expect(normalizeAgentForPromptKey("Sisyphus - Ultraworker")).toBe("sisyphus")
   })
 
   it("preserves custom agents", () => {
@@ -216,15 +216,15 @@ describe("AGENT_DISPLAY_NAMES", () => {
   it("contains all expected agent mappings", () => {
     // given expected mappings
     const expectedMappings = {
-      sisyphus: "Sisyphus (Ultraworker)",
-      hephaestus: "Hephaestus (Deep Agent)",
-      prometheus: "Prometheus (Plan Builder)",
-      atlas: "Atlas (Plan Executor)",
+      sisyphus: "Sisyphus - Ultraworker",
+      hephaestus: "Hephaestus - Deep Agent",
+      prometheus: "Prometheus - Plan Builder",
+      atlas: "Atlas - Plan Executor",
       "sisyphus-junior": "Sisyphus-Junior",
-      metis: "Metis (Plan Consultant)",
-      momus: "Momus (Plan Critic)",
-      athena: "Athena (Council)",
-      "athena-junior": "Athena-Junior (Council)",
+      metis: "Metis - Plan Consultant",
+      momus: "Momus - Plan Critic",
+      athena: "Athena - Council",
+      "athena-junior": "Athena-Junior - Council",
       oracle: "oracle",
       librarian: "librarian",
       explore: "explore",
diff --git a/src/shared/agent-display-names.ts b/src/shared/agent-display-names.ts
index 532155ccc..d42493fc6 100644
--- a/src/shared/agent-display-names.ts
+++ b/src/shared/agent-display-names.ts
@@ -4,15 +4,15 @@
  * Display names include suffixes for UI/logs (e.g., "Sisyphus (Ultraworker)").
  */
 export const AGENT_DISPLAY_NAMES: Record<string, string> = {
-  sisyphus: "Sisyphus (Ultraworker)",
-  hephaestus: "Hephaestus (Deep Agent)",
-  prometheus: "Prometheus (Plan Builder)",
-  atlas: "Atlas (Plan Executor)",
+  sisyphus: "Sisyphus - Ultraworker",
+  hephaestus: "Hephaestus - Deep Agent",
+  prometheus: "Prometheus - Plan Builder",
+  atlas: "Atlas - Plan Executor",
   "sisyphus-junior": "Sisyphus-Junior",
-  metis: "Metis (Plan Consultant)",
-  momus: "Momus (Plan Critic)",
-  athena: "Athena (Council)",
-  "athena-junior": "Athena-Junior (Council)",
+  metis: "Metis - Plan Consultant",
+  momus: "Momus - Plan Critic",
+  athena: "Athena - Council",
+  "athena-junior": "Athena-Junior - Council",
   oracle: "oracle",
   librarian: "librarian",
   explore: "explore",
diff --git a/src/tools/delegate-task/zauc-mocks-subagent-resolver/subagent-resolver.test.ts b/src/tools/delegate-task/zauc-mocks-subagent-resolver/subagent-resolver.test.ts
index e21b104fb..2a38af4d7 100644
--- a/src/tools/delegate-task/zauc-mocks-subagent-resolver/subagent-resolver.test.ts
+++ b/src/tools/delegate-task/zauc-mocks-subagent-resolver/subagent-resolver.test.ts
@@ -675,7 +675,7 @@ describe("resolveSubagentExecution - agent name sanitization", () => {
     })
     const args = createBaseArgs({ subagent_type: "\\hephaestus\\" })
     const executorCtx = createExecutorContext(async () => ([
-      { name: "Hephaestus (Deep Agent)", mode: "subagent", model: "openai/gpt-5.3-codex" },
+      { name: "Hephaestus - Deep Agent", mode: "subagent", model: "openai/gpt-5.3-codex" },
     ]))
 
     //#when
@@ -683,7 +683,7 @@ describe("resolveSubagentExecution - agent name sanitization", () => {
 
     //#then
     expect(result.error).toBeUndefined()
-    expect(result.agentToUse).toBe("Hephaestus (Deep Agent)")
+    expect(result.agentToUse).toBe("Hephaestus - Deep Agent")
     cacheSpy.mockRestore()
   })