Forward OpenCode Go worker session IDs without a catalog

src/config.test.ts

@@ -1423,6 +1423,7 @@ describe("buildGoSource", () => {
       id: "opencode-go",
       apiKey: "sk-go",
       model: "kimi-k2.7-code",
+      sessionId: "sess-1",
     });
 
     expect(source.provider).toBe("opencode-go");

src/config/index.ts

@@ -383,7 +383,7 @@ export function buildGoSource(fields: {
   id: string;
   apiKey?: string;
   model: string;
-  sessionId?: string;
+  sessionId: string;
   reasoningEffort?: ReasoningEffort;
 }): InferenceSource {
   const endpoint = resolveGoEndpoint(fields.model);
@@ -400,13 +400,9 @@ export function buildGoSource(fields: {
       model: fields.model,
       defaults: {
         maxTokens: SOURCE_MAX_TOKENS,
-        ...(fields.sessionId !== undefined
-          ? {
-              providerOptions: {
-                [OPENCODE_SESSION_ID_OPTION]: fields.sessionId,
-              },
-            }
-          : {}),
+        providerOptions: {
+          [OPENCODE_SESSION_ID_OPTION]: fields.sessionId,
+        },
       },
     };
   }
@@ -419,14 +415,10 @@ export function buildGoSource(fields: {
       model: fields.model,
       defaults: {
         maxTokens: SOURCE_MAX_TOKENS,
-        ...(fields.sessionId !== undefined
-          ? {
-              providerOptions: {
-                [OPENAI_SESSION_ID_OPTION]: fields.sessionId,
-                [OPENCODE_SESSION_ID_OPTION]: fields.sessionId,
-              },
-            }
-          : {}),
+        providerOptions: {
+          [OPENAI_SESSION_ID_OPTION]: fields.sessionId,
+          [OPENCODE_SESSION_ID_OPTION]: fields.sessionId,
+        },
       },
     };
   }
@@ -446,14 +438,10 @@ export function buildGoSource(fields: {
     provider: OPENCODE_GO_PROVIDER_ID,
     defaults: {
       ...source.defaults,
-      ...(fields.sessionId !== undefined
-        ? {
-            providerOptions: {
-              ...(source.defaults?.providerOptions ?? {}),
-              [OPENCODE_SESSION_ID_OPTION]: fields.sessionId,
-            },
-          }
-        : {}),
+      providerOptions: {
+        ...(source.defaults?.providerOptions ?? {}),
+        [OPENCODE_SESSION_ID_OPTION]: fields.sessionId,
+      },
     },
   };
 }

src/subagent/run-source.test.ts

@@ -1,6 +1,7 @@
 import { describe, expect, test } from "bun:test";
 
 import { KEYLESS_API_KEY } from "../config/index.js";
+import { OPENCODE_GO_BASE_URL } from "../../packages/opencode-go/src/index.js";
 import { buildSubAgentPrimarySource } from "./run.js";
 
 describe("buildSubAgentPrimarySource", () => {
@@ -22,4 +23,61 @@ describe("buildSubAgentPrimarySource", () => {
       model: "qwen3",
     });
   });
+
+  test.each([
+    ["canonical provider id", "opencode-go", "https://example.com/v1"],
+    ["canonical base URL", "custom-go", OPENCODE_GO_BASE_URL],
+  ])(
+    "routes no-catalog OpenCode Go by %s with a non-empty session ID",
+    (_, providerName, baseURL) => {
+      const bundle = buildSubAgentPrimarySource({
+        providerName,
+        baseURL,
+        apiKey: "sk-go",
+        model: "gpt-5.6-luna",
+      });
+
+      const source = bundle.sources[0];
+      const sessionId = source?.defaults?.providerOptions?.opencodeSessionId;
+      expect(bundle.defaultSource).toBe(providerName);
+      expect(source).toMatchObject({
+        id: providerName,
+        provider: "openai-responses",
+        apiKey: "sk-go",
+        model: "gpt-5.6-luna",
+      });
+      expect(typeof sessionId).toBe("string");
+      expect(sessionId).not.toHaveLength(0);
+      expect(source?.defaults?.providerOptions?.openaiSessionId).toBe(
+        sessionId,
+      );
+    },
+  );
+
+  test("forwards a session ID through the catalog OpenCode Go path", () => {
+    const bundle = buildSubAgentPrimarySource(
+      {
+        providerName: "opencode-go",
+        baseURL: OPENCODE_GO_BASE_URL,
+        apiKey: "sk-go",
+        model: "kimi-k2.7-code",
+      },
+      [
+        {
+          name: "opencode-go",
+          baseURL: OPENCODE_GO_BASE_URL,
+          apiKey: "sk-go",
+          models: ["kimi-k2.7-code"],
+          opencodeGo: true,
+        },
+      ],
+    );
+
+    const source = bundle.sources[0];
+    const sessionId = source?.defaults?.providerOptions?.opencodeSessionId;
+    expect(bundle.defaultSource).toBe("opencode-go");
+    expect(source?.provider).toBe("opencode-go");
+    expect(typeof sessionId).toBe("string");
+    expect(sessionId).not.toHaveLength(0);
+  });
 });

src/subagent/run.ts

@@ -36,6 +36,7 @@ import type {
 
 import {
   buildBifrostSource,
+  buildGoSource,
   buildOpenAISource,
   type ProviderCatalogEntry,
 } from "../config/index.js";
@@ -63,6 +64,7 @@ import {
 import { createCodexReadRawFile } from "../agent/codex-read-raw-file.js";
 
 import { isCodexProviderName } from "../config/codex-providers.js";
+import { isOpenCodeGoProvider } from "../../packages/opencode-go/src/index.js";
 import { createCompositeBlobReader } from "../agent/lazy-blob-reader.js";
 
 import { buildSubAgentSystemPrompt } from "../agent/prompts.js";
@@ -216,11 +218,12 @@ export function buildSubAgentPrimarySource(
   catalog?: readonly ProviderCatalogEntry[],
   settings?: Settings,
 ) {
+  const sessionId = generateSessionId();
   if (catalog !== undefined) {
     const source = buildInferenceSourceForRef(
       { provider: provider.providerName, model: provider.model },
       {
-        sessionId: generateSessionId(),
+        sessionId,
         catalog,
         ...(provider.reasoningEffort !== undefined
           ? { reasoningEffort: provider.reasoningEffort }
@@ -230,6 +233,23 @@ export function buildSubAgentPrimarySource(
     );
     if (source !== null) return { sources: [source], defaultSource: source.id };
   }
+  if (
+    isOpenCodeGoProvider({
+      name: provider.providerName,
+      baseURL: provider.baseURL,
+    })
+  ) {
+    const source = buildGoSource({
+      id: provider.providerName,
+      ...(provider.apiKey !== undefined ? { apiKey: provider.apiKey } : {}),
+      model: provider.model,
+      sessionId,
+      ...(provider.reasoningEffort !== undefined
+        ? { reasoningEffort: provider.reasoningEffort }
+        : {}),
+    });
+    return { sources: [source], defaultSource: source.id };
+  }
   const build =
     provider.bifrostVirtualKey === true
       ? buildBifrostSource