fix: unify agent display names and strip invisible sort prefixes

- Replace getAgentRuntimeName with getAgentDisplayName for consistency
- Add stripAgentListSortPrefix helper to normalize agent names
- Strip sort prefixes in subagent-resolver and sync-executor
- Backfill canonical names for core agents when builtin configs omit name
- Update tests to match new behavior

src/plugin-handlers/agent-key-remapper.test.ts

@@ -1,6 +1,6 @@
 import { describe, it, expect } from "bun:test"
 import { remapAgentKeysToDisplayNames } from "./agent-key-remapper"
-import { getAgentDisplayName, getAgentRuntimeName } from "../shared/agent-display-names"
+import { getAgentDisplayName } from "../shared/agent-display-names"
 
 describe("remapAgentKeysToDisplayNames", () => {
   it("remaps known agent keys to display names", () => {
@@ -106,7 +106,7 @@ describe("remapAgentKeysToDisplayNames", () => {
     }
   })
 
-  it("preserves clean keys but rewrites core agent name fields to list-display names for tab cycling", () => {
+  it("preserves clean keys and rewrites core agent name fields to canonical display names", () => {
     // given agents with raw config-key names
     const agents = {
       sisyphus: { name: "sisyphus", prompt: "test", mode: "primary" },
@@ -119,7 +119,7 @@ describe("remapAgentKeysToDisplayNames", () => {
     // when remapping
     const result = remapAgentKeysToDisplayNames(agents)
 
-    // then keys stay HTTP-header-safe, but nested names carry stable list ordering
+    // then keys stay HTTP-header-safe, and nested names match the lookup-safe display names
     expect(Object.keys(result).slice(0, 4)).toEqual([
       getAgentDisplayName("sisyphus"),
       getAgentDisplayName("hephaestus"),
@@ -127,25 +127,60 @@ describe("remapAgentKeysToDisplayNames", () => {
       getAgentDisplayName("atlas"),
     ])
     expect(result[getAgentDisplayName("sisyphus")]).toEqual({
-      name: getAgentRuntimeName("sisyphus"),
+      name: getAgentDisplayName("sisyphus"),
       prompt: "test",
       mode: "primary",
     })
     expect(result[getAgentDisplayName("hephaestus")]).toEqual({
-      name: getAgentRuntimeName("hephaestus"),
+      name: getAgentDisplayName("hephaestus"),
       prompt: "test",
       mode: "primary",
     })
     expect(result[getAgentDisplayName("prometheus")]).toEqual({
-      name: getAgentRuntimeName("prometheus"),
+      name: getAgentDisplayName("prometheus"),
       prompt: "test",
       mode: "all",
     })
     expect(result[getAgentDisplayName("atlas")]).toEqual({
-      name: getAgentRuntimeName("atlas"),
+      name: getAgentDisplayName("atlas"),
       prompt: "test",
       mode: "primary",
     })
     expect(result.oracle).toEqual({ name: "oracle", prompt: "test", mode: "subagent" })
   })
+
+  it("backfills canonical display names for core agents when builtin configs omit name", () => {
+    // given builtin-style configs without name fields
+    const agents = {
+      sisyphus: { prompt: "test", mode: "primary" },
+      hephaestus: { prompt: "test", mode: "primary" },
+      prometheus: { prompt: "test", mode: "all" },
+      atlas: { prompt: "test", mode: "primary" },
+    }
+
+    // when remapping
+    const result = remapAgentKeysToDisplayNames(agents)
+
+    // then OpenCode receives lookup-safe display names and uses order for sorting
+    expect(result[getAgentDisplayName("sisyphus")]).toEqual({
+      name: getAgentDisplayName("sisyphus"),
+      prompt: "test",
+      mode: "primary",
+    })
+    expect(result[getAgentDisplayName("hephaestus")]).toEqual({
+      name: getAgentDisplayName("hephaestus"),
+      prompt: "test",
+      mode: "primary",
+    })
+    expect(result[getAgentDisplayName("prometheus")]).toEqual({
+      name: getAgentDisplayName("prometheus"),
+      prompt: "test",
+      mode: "all",
+    })
+    expect(result[getAgentDisplayName("atlas")]).toEqual({
+      name: getAgentDisplayName("atlas"),
+      prompt: "test",
+      mode: "primary",
+    })
+  })
 })