fix(opencode): OpenCode 2 threads see T3 Code's MCP tools on their first turn

apps/server/src/orchestration-v2/Adapters/OpenCode2AdapterV2.test.ts

@@ -4150,26 +4150,37 @@ it.layer(McpProviderSessions.layer)("OpenCode2 adapter", (it) => {
         promptAccepted,
         event("session.execution.succeeded", { sessionID: SESSION }),
       ];
+      const prompts: Array<unknown> = [];
       // Idle Location eviction drops OpenCode's runtime MCP servers without a reconnect.
-      const { runtime, thread } = yield* resumed([
-        add,
-        reply("mcp.add", null),
-        ...turn,
-        add,
-        reply("mcp.add", { status: 500, body: { message: "MCP unavailable" } }),
-        out("session.instructions.entry.put", {
-          sessionID: SESSION,
-          key: "t3-code",
-          value: buildRuntimeInstructions({ harness: "OpenCode", model: bigPickle.model }),
-        }),
-        reply("session.instructions.entry.put", null),
-        ...turn,
-        out("mcp.remove", { server, "location[directory]": WORK }),
-        reply("mcp.remove", null),
-      ]);
+      const { runtime, thread } = yield* resumed(
+        [
+          add,
+          reply("mcp.add", null),
+          ...turn,
+          add,
+          reply("mcp.add", { status: 500, body: { message: "MCP unavailable" } }),
+          out("session.instructions.entry.put", {
+            sessionID: SESSION,
+            key: "t3-code",
+            value: buildRuntimeInstructions({ harness: "OpenCode", model: bigPickle.model }),
+          }),
+          reply("session.instructions.entry.put", null),
+          ...turn,
+          out("mcp.remove", { server, "location[directory]": WORK }),
+          reply("mcp.remove", null),
+        ],
+        { onPrompt: (input) => prompts.push(input) },
+      );
       for (let index = 0; index < 2; index++) {
         const terminal = yield* terminalOf(runtime).pipe(Effect.forkScoped);
-        yield* runtime.startTurn(turnInput(thread));
+        const started = yield* runtime.startTurn(turnInput(thread)).pipe(Effect.forkScoped);
+        // OpenCode before 2.2.6 loads a newly added server's tools after a debounce.
+        if (index === 0) {
+          yield* TestClock.adjust("249 millis");
+          assert.lengthOf(prompts, 0, "prompted before OpenCode loaded the new MCP server's tools");
+          yield* TestClock.adjust("1 millis");
+        }
+        yield* Fiber.join(started);
         assert.equal((yield* Fiber.join(terminal))?.status, "completed");
       }
     }).pipe(Effect.scoped),
@@ -4230,7 +4241,11 @@ it.layer(McpProviderSessions.layer)("OpenCode2 adapter", (it) => {
         runtimePolicy: policy(),
       });
       const terminal = yield* terminalOf(runtime).pipe(Effect.forkScoped);
-      yield* runtime.startTurn({ ...turnInput(thread), threadId: child });
+      const started = yield* runtime
+        .startTurn({ ...turnInput(thread), threadId: child })
+        .pipe(Effect.forkScoped);
+      yield* TestClock.adjust("250 millis");
+      yield* Fiber.join(started);
       assert.equal((yield* Fiber.join(terminal))?.status, "completed");
       yield* runtime.unloadThread!({ providerThread: thread });
     }).pipe(Effect.scoped),

packages/provider-opencode/src/server/v2/adapter.ts

@@ -592,6 +592,7 @@ const RECONNECT_WAIT = "30 seconds";
 const LOST_BACKGROUND =
   "T3 Code lost its connection to OpenCode while this subagent ran, so its result is not shown.";
 const INVENTORY_TIMEOUT = "5 seconds";
+const MCP_TOOL_RELOAD_SETTLE = "250 millis";
 const ACTIVE_CHECK_TIMEOUT = "5 seconds";
 // Other failures may still have admitted the prompt.
 const CLEAR_PROMPT_REJECTIONS: ReadonlySet<string> = new Set([
@@ -4060,6 +4061,7 @@ export const make = Effect.fn("OpenCode2Adapter.make")(function* (instanceId: Pr
       // Re-adding an unchanged config keeps its existing connection.
       let mcpAvailable = false;
       if (wanted !== undefined) {
+        const fresh = state.mcp === undefined;
         mcpAvailable = yield* client.mcp
           .add({
             server: name,
@@ -4081,6 +4083,10 @@ export const make = Effect.fn("OpenCode2Adapter.make")(function* (instanceId: Pr
             ),
           );
         if (mcpAvailable) state.mcp = wanted;
+        // Before 2.2.6, OpenCode loads a new server's tools 100 ms after it connects, and a prompt sent sooner lacks them.
+        if (mcpAvailable && fresh && compareSemverVersions(connection.version, "2.2.6") < 0) {
+          yield* Effect.sleep(MCP_TOOL_RELOAD_SETTLE);
+        }
       }
       const instructions = [
         buildRuntimeInstructions({ harness: "OpenCode", model: turnInput.modelSelection.model }),