fix(opencode): trust discovered modes, don't inject hardcoded defaults (#1366)

* fix(opencode): trust discovered modes instead of always injecting defaults

When OpenCode reports its available agents, respect that list exactly
rather than seeding from DEFAULT_MODES first. This means users who have
intentionally disabled modes (e.g. Plan) in their OpenCode config will
no longer see those modes surfaced in Paseo.

DEFAULT_MODES is still used as a fallback when discovery returns nothing
(e.g. OpenCode unreachable or no agents configured).

* test(opencode): update mode discovery expectations

* test(opencode): expect discovered custom modes only

packages/server/src/server/agent/providers/opencode-agent.full-access.test.ts

@@ -63,7 +63,7 @@ function questionEvent(questionOverrides: Record<string, unknown> = {}): unknown
 }
 
 describe("OpenCode auto_accept feature", () => {
-  test("lists OpenCode modes without the legacy virtual full-access mode", async () => {
+  test("lists discovered OpenCode modes without injecting defaults", async () => {
     const { runtime } = mockOpenCodeClient({
       agents: [
         { name: "build", mode: "primary", hidden: false, description: "Build agent" },
@@ -74,7 +74,16 @@ describe("OpenCode auto_accept feature", () => {
     const client = new OpenCodeAgentClient(createTestLogger(), undefined, { runtime });
     const modes = await client.listModes({ cwd: "/tmp/project", force: false });
 
-    expect(modes.map((mode) => mode.id)).toEqual(["build", "plan", "paseo-custom"]);
+    expect(modes.map((mode) => mode.id)).toEqual(["build", "paseo-custom"]);
+  });
+
+  test("falls back to default OpenCode modes when discovery returns no modes", async () => {
+    const { runtime } = mockOpenCodeClient({ agents: [] });
+
+    const client = new OpenCodeAgentClient(createTestLogger(), undefined, { runtime });
+    const modes = await client.listModes({ cwd: "/tmp/project", force: false });
+
+    expect(modes.map((mode) => mode.id)).toEqual(["build", "plan"]);
   });
 
   test("lists auto accept as a provider feature", async () => {

packages/server/src/server/agent/providers/opencode-agent.test.ts

@@ -404,8 +404,7 @@ describe("OpenCodeAgentClient adapter smoke tests", () => {
 
     const modes = await session.getAvailableModes();
 
-    expect(modes.some((mode) => mode.id === "build")).toBe(true);
-    expect(modes.some((mode) => mode.id === "plan")).toBe(true);
+    expect(modes.map((mode) => mode.id)).toEqual(["paseo-test-custom"]);
 
     const custom = modes.find((mode) => mode.id === "paseo-test-custom");
     expect(custom).toBeDefined();

packages/server/src/server/agent/providers/opencode-agent.ts

@@ -591,14 +591,16 @@ function mapOpenCodeAgentToMode(agent: {
 }
 
 function mergeOpenCodeModes(discoveredModes: AgentMode[]): AgentMode[] {
-  const modesById = new Map(DEFAULT_MODES.map((mode) => [mode.id, mode]));
-  for (const mode of discoveredModes) {
-    if (mode.id === OPENCODE_LEGACY_FULL_ACCESS_MODE_ID) {
-      continue;
-    }
-    modesById.set(mode.id, mode);
+  const filtered = discoveredModes.filter(
+    (mode) => mode.id !== OPENCODE_LEGACY_FULL_ACCESS_MODE_ID,
+  );
+  // When discovery returns results, trust them exactly — don't inject hardcoded
+  // defaults that the user may have intentionally disabled in their OpenCode config.
+  // Fall back to DEFAULT_MODES only when discovery produced nothing.
+  if (filtered.length > 0) {
+    return sortOpenCodeModes(filtered);
   }
-  return sortOpenCodeModes(Array.from(modesById.values()));
+  return sortOpenCodeModes([...DEFAULT_MODES]);
 }
 
 function sortOpenCodeModes(modes: AgentMode[]): AgentMode[] {