Resolve Copilot sub-agent models in the harness (CLI and SDK) and fail closed

actions/setup/js/copilot_sdk_driver.cjs

@@ -13,6 +13,7 @@
  *   COPILOT_MODEL                            — model override (optional)
  *   GH_AW_COPILOT_SDK_MULTI_PROVIDER_JSON   — JSON-encoded multi-provider config (required).
  *                                             Shape: { model, providers: NamedProviderConfig[], models: ProviderModelConfig[] }
+ *   GH_AW_COPILOT_SDK_SUBAGENT_MODELS       — JSON map of custom agent name → model resolved by the harness (optional)
  *   GH_AW_COPILOT_SDK_SERVER_ARGS           — JSON-encoded allow-tool sidecar args (set by the engine)
  *
  * The sidecar is started and stopped by the harness; the driver only opens a

actions/setup/js/copilot_sdk_driver.test.cjs

@@ -1,4 +1,4 @@
-import { describe, it, expect, vi, beforeAll, afterAll } from "vitest";
+import { describe, it, expect, vi, beforeAll, afterAll, afterEach } from "vitest";
 import { createRequire } from "module";
 import * as fs from "fs";
 import * as path from "path";
@@ -31,6 +31,10 @@ describe("copilot_sdk_driver.cjs", () => {
   });
 
   describe("runWithCopilotSDK", () => {
+    afterEach(() => {
+      vi.unstubAllEnvs();
+    });
+
     it.each([
       ["gpt-5.4", "claude-sonnet-4.6", "copilot-responses", "copilot-completions"],
       ["claude-sonnet-4.6", "gpt-5.4", "copilot-completions", "copilot-responses"],
@@ -43,9 +47,10 @@ describe("copilot_sdk_driver.cjs", () => {
         path.join(workspace, ".github/agents/researcher.agent.md"),
         `---\nname: researcher\ndescription: >-\n  Research across\n  providers\ntools:\n  - read\n  - grep\nmodel: copilot/${agentModel}\n---\nResearch carefully.\n`
       );
-      fs.writeFileSync(path.join(workflow, ".github/agents/workflow.agent.md"), "---\nname: workflow-agent\nmodel: medium\ntools: read, grep\n---\nWorkflow prompt.");
+      fs.writeFileSync(path.join(workflow, ".github/agents/workflow.agent.md"), "---\nname: workflow-agent\ntools: read, grep\n---\nWorkflow prompt.");
       for (const alias of ["small", "large"]) fs.writeFileSync(path.join(workflow, `.github/agents/${alias}.agent.md`), `---\nmodel: ${alias}\n---\nAlias prompt.`);
-      fs.writeFileSync(path.join(workflow, ".github/agents/unknown.agent.md"), "---\nname: unknown-agent\nmodel: unavailable-model\n---\nKeep this agent.");
+      // The harness resolves aliases before the driver starts; the driver uses those models, not the session model.
+      vi.stubEnv("GH_AW_COPILOT_SDK_SUBAGENT_MODELS", JSON.stringify({ small: `${agentProvider}/${agentModel}`, large: agentModel }));
       const createSession = vi.fn().mockResolvedValue({
         sessionId: `${sessionProvider}-agent-session`,
         on: () => {},
@@ -90,21 +95,48 @@ describe("copilot_sdk_driver.cjs", () => {
           customAgents: expect.arrayContaining([
             { name: "researcher", displayName: "researcher", description: "Research across providers", tools: ["read", "grep"], prompt: "Research carefully.", model: `${agentProvider}/${agentModel}` },
             { name: "workflow-agent", displayName: "workflow-agent", tools: ["read", "grep"], prompt: "Workflow prompt.", model: `${sessionProvider}/${sessionModel}` },
-            { name: "unknown-agent", displayName: "unknown-agent", prompt: "Keep this agent.", model: `${sessionProvider}/${sessionModel}` },
-            { name: "small", displayName: "small", prompt: "Alias prompt.", model: `${sessionProvider}/${sessionModel}` },
-            { name: "large", displayName: "large", prompt: "Alias prompt.", model: `${sessionProvider}/${sessionModel}` },
+            { name: "small", displayName: "small", prompt: "Alias prompt.", model: `${agentProvider}/${agentModel}` },
+            { name: "large", displayName: "large", prompt: "Alias prompt.", model: `${agentProvider}/${agentModel}` },
           ]),
         })
       );
-      expect(logger).toHaveBeenCalledWith(expect.stringMatching(/warning:.*unknown-agent.*unavailable-model.*session model/i));
+    });
+
+    it.each(["medium", "GPT-5.4 (copilot)"])("gives a repository agent whose model %s the harness could not resolve the session model with a warning", async agentModel => {
+      const workflow = path.join(testSessionStateDir, `unresolved-${agentModel.replace(/\W+/g, "-")}-workflow`);
+      fs.mkdirSync(path.join(workflow, ".github/agents"), { recursive: true });
+      fs.writeFileSync(path.join(workflow, ".github/agents/unknown.agent.md"), `---\nname: unknown-agent\nmodel: ${agentModel}\n---\nUnknown model.`);
+      // The harness recorded the failure and left the repository agent out of the resolved map.
+      vi.stubEnv("GH_AW_COPILOT_SDK_SUBAGENT_MODELS", "{}");
+      const sessionId = `unresolved-${agentModel.replace(/\W+/g, "-")}-session`;
+      const createSession = vi.fn().mockResolvedValue({ sessionId, on: () => {}, sendAndWait: vi.fn().mockResolvedValue({ data: { content: "done" } }), disconnect: vi.fn().mockResolvedValue(undefined) });
+      class FakeCopilotClient {
+        start = vi.fn().mockResolvedValue(undefined);
+        createSession = createSession;
+        stop = vi.fn().mockResolvedValue(undefined);
+      }
+      const logger = vi.fn();
+      const result = await runWithCopilotSDK({
+        sdkUri: "http://127.0.0.1:3002",
+        prompt: "test prompt",
+        model: "copilot/gpt-5.4",
+        models: [{ id: "gpt-5.4", provider: "copilot-responses" }],
+        providers: [{ name: "copilot-responses", type: "openai", baseUrl: "http://api-proxy:10002", wireApi: "responses" }],
+        workingDirectory: workflow,
+        agentsBaseDir: workflow,
+        bare: true,
+        logger,
+        sdkModule: { CopilotClient: FakeCopilotClient, RuntimeConnection: { forUri: vi.fn(() => ({})) }, approveAll: () => "allow" },
+      });
+      expect(result.exitCode).toBe(0);
+      expect(createSession.mock.calls[0][0].customAgents).toEqual([{ name: "unknown-agent", displayName: "unknown-agent", prompt: "Unknown model.", model: "copilot-responses/gpt-5.4" }]);
+      expect(logger).toHaveBeenCalledWith(expect.stringMatching(/warning:.*unknown-agent.*session model/i));
       const captured = fs
-        .readFileSync(path.join(testSessionStateDir, `${sessionProvider}-agent-session/events.jsonl`), "utf8")
+        .readFileSync(path.join(testSessionStateDir, `${sessionId}/events.jsonl`), "utf8")
         .trim()
         .split("\n")
         .map(JSON.parse);
-      expect(captured.filter(event => event.type === "subagent.model_unavailable")).toEqual([
-        expect.objectContaining({ data: { agentName: "unknown-agent", declaredModel: "unavailable-model", model: `${sessionProvider}/${sessionModel}` } }),
-      ]);
+      expect(captured.filter(event => event.type === "subagent.model_unavailable")).toEqual([expect.objectContaining({ data: { agentName: "unknown-agent", declaredModel: agentModel, model: "copilot-responses/gpt-5.4" } })]);
     });
 
     it("captures ephemeral selection and final model results including BYOK and subagent context", async () => {

actions/setup/js/copilot_sdk_session.cjs

@@ -111,6 +111,20 @@ function resolveCopilotSDKWorkingDirectory() {
   return path.resolve(process.env.GITHUB_WORKSPACE || process.cwd(), process.env.GH_AW_ENGINE_CWD || ".");
 }
 
+/**
+ * Parse GH_AW_COPILOT_SDK_SUBAGENT_MODELS: custom agent name → model resolved by the harness.
+ * @param {string | undefined} value
+ * @returns {Record<string, string>}
+ */
+function parseSubagentModelsJson(value) {
+  if (!value) return {};
+  const parsed = JSON.parse(value);
+  if (!parsed || typeof parsed !== "object" || Array.isArray(parsed) || !Object.values(parsed).every(model => typeof model === "string")) {
+    throw new Error("GH_AW_COPILOT_SDK_SUBAGENT_MODELS must map custom agent names to models");
+  }
+  return parsed;
+}
+
 /**
  * Run a Copilot agentic session using the @github/copilot-sdk.
  *
@@ -369,16 +383,24 @@ async function runWithCopilotSDK({
     const providerConfig = providers && providerModels ? { providers, models: providerModels } : null;
     const sessionModel = providerConfig ? qualifyModelForMultiProvider(requestedModel, providerConfig) : requestedModel;
     if (providerConfig && !sessionModel) throw new Error(`Cannot qualify session model "${requestedModel || "(none)"}" against the configured provider models`);
+    // The harness resolves sub-agent models (aliases included) before the driver starts and
+    // stops the run when a workflow-declared sub-agent fails. A repository agent whose model
+    // the harness could not resolve is absent from the map and inherits the session model.
+    const resolvedSubagentModels = parseSubagentModelsJson(process.env.GH_AW_COPILOT_SDK_SUBAGENT_MODELS);
     const unavailableModels = [];
     const customAgents = loadCopilotSDKCustomAgents(workingDirectory, agentsBaseDir, log).map(agent => {
-      const requested = agent.model;
-      const alias = !requested || ["small", "medium", "large"].includes(requested.toLowerCase());
-      const qualified = alias ? sessionModel : providerConfig ? qualifyModelForMultiProvider(requested, providerConfig) : requested;
-      if (!alias && !qualified) {
-        log(`warning: custom agent "${agent.name}" model "${requested}" is not in the configured provider models; using session model "${sessionModel || "(none)"}"`);
-        unavailableModels.push({ agentName: agent.name, declaredModel: requested, model: sessionModel || undefined });
+      if (!agent.model || agent.model.trim().toLowerCase() === "inherited") return { ...agent, model: sessionModel || undefined };
+      if (Object.prototype.hasOwnProperty.call(resolvedSubagentModels, agent.name)) {
+        const resolved = resolvedSubagentModels[agent.name];
+        const qualified = providerConfig ? qualifyModelForMultiProvider(resolved, providerConfig) : resolved;
+        if (!qualified) throw new Error(`Cannot qualify custom agent "${agent.name}" model "${resolved}" against the configured provider models`);
+        return { ...agent, model: qualified };
       }
-      return { ...agent, model: qualified || sessionModel || undefined };
+      const qualified = providerConfig ? qualifyModelForMultiProvider(agent.model, providerConfig) : agent.model;
+      if (qualified) return { ...agent, model: qualified };
+      log(`warning: custom agent "${agent.name}" model "${agent.model}" is not in the configured provider models; using session model "${sessionModel || "(none)"}"`);
+      unavailableModels.push({ agentName: agent.name, declaredModel: agent.model, model: sessionModel || undefined });
+      return { ...agent, model: sessionModel || undefined };
     });
     const skillsDirectory = path.resolve(agentsBaseDir, ".github", "skills");
     const skillsStat = fs.lstatSync(skillsDirectory, { throwIfNoEntry: false });

actions/setup/js/copilot_sdk_session.test.cjs

@@ -141,6 +141,8 @@ describe("copilot_sdk_session runtime configuration", () => {
     const app = path.join(base, "packages/app");
     fs.mkdirSync(path.join(app, ".github/agents"), { recursive: true });
     fs.writeFileSync(path.join(app, ".github/agents/local.agent.md"), "---\nmodel: small\n---\nApp agent.");
+    // The harness resolved `small` before the driver started.
+    vi.stubEnv("GH_AW_COPILOT_SDK_SUBAGENT_MODELS", JSON.stringify({ local: "claude-sonnet-4.6" }));
     vi.stubEnv("GITHUB_WORKSPACE", base);
     vi.spyOn(process, "cwd").mockReturnValue(app);
     const createSession = vi.fn().mockResolvedValue({

actions/setup/js/fixtures/awf-config-models-copilot-sub-agents-39304573724.json

@@ -0,0 +1,67 @@
+{
+  "apiProxy": {
+    "models": {
+      "agent": ["sonnet-6x", "gpt-6", "gpt-5.4", "gpt-5.5", "gpt-5.6", "gpt-5.3", "gemini-pro", "any"],
+      "antigravity": ["copilot/antigravity*", "google/antigravity*", "gemini/antigravity*"],
+      "any": ["copilot/*", "anthropic/*", "openai/*", "google/*", "gemini/*"],
+      "auto": ["copilot/auto", "large"],
+      "claude": ["agent"],
+      "codex": ["agent"],
+      "coding": ["copilot/gpt-5*codex*", "openai/gpt-5*codex*", "gpt-5-codex", "kimi"],
+      "computer-use": ["copilot/*computer-use*", "google/*computer-use*", "gemini/*computer-use*", "openai/*computer-use*"],
+      "copilot": ["agent"],
+      "deep-research": ["copilot/deep-research*", "copilot/o3-deep-research*", "copilot/o4-mini-deep-research*", "google/deep-research*", "gemini/deep-research*", "openai/o3-deep-research*", "openai/o4-mini-deep-research*"],
+      "detection": ["small"],
+      "evals": ["small"],
+      "fable": ["copilot/*fable*", "anthropic/*fable*"],
+      "gemini": ["agent"],
+      "gemini-3-flash": ["copilot/gemini-3*flash*", "google/gemini-3*flash*", "gemini/gemini-3*flash*"],
+      "gemini-3-pro": ["copilot/gemini-3*pro*", "google/gemini-3*pro*", "google/nano-banana*", "gemini/gemini-3*pro*"],
+      "gemini-3.1-flash": ["copilot/gemini-3.1*flash*", "google/gemini-3.1*flash*", "gemini/gemini-3.1*flash*"],
+      "gemini-3.1-pro": ["copilot/gemini-3.1*pro*", "google/gemini-3.1*pro*", "gemini/gemini-3.1*pro*"],
+      "gemini-3.5-flash": ["copilot/gemini-3.5*flash*", "google/gemini-3.5*flash*", "gemini/gemini-3.5*flash*"],
+      "gemini-3.6-flash": ["copilot/gemini-3.6*flash*", "google/gemini-3.6*flash*", "gemini/gemini-3.6*flash*"],
+      "gemini-3.7-flash": ["copilot/gemini-3.7*flash*", "google/gemini-3.7*flash*", "gemini/gemini-3.7*flash*"],
+      "gemini-3.8-flash": ["copilot/gemini-3.8*flash*", "google/gemini-3.8*flash*", "gemini/gemini-3.8*flash*"],
+      "gemini-flash": ["copilot/gemini-*flash*", "google/gemini-*flash*", "gemini/gemini-*flash*"],
+      "gemini-flash-lite": ["copilot/gemini-*flash*lite*", "google/gemini-*flash*lite*", "gemini/gemini-*flash*lite*"],
+      "gemini-omni": ["copilot/gemini-omni*", "google/gemini-omni*", "gemini/gemini-omni*"],
+      "gemini-pro": ["copilot/gemini-*pro*", "google/gemini-*pro*", "gemini/gemini-*pro*"],
+      "gemma": ["copilot/gemma*", "google/gemma*", "gemini/gemma*"],
+      "gpt-5": ["copilot/gpt-5*", "openai/gpt-5*"],
+      "gpt-5-codex": ["copilot/gpt-5*codex*", "openai/gpt-5*codex*"],
+      "gpt-5-mini": ["copilot/gpt-5*mini*", "openai/gpt-5*mini*"],
+      "gpt-5-nano": ["copilot/gpt-5*nano*", "openai/gpt-5*nano*"],
+      "gpt-5-pro": ["copilot/gpt-5*pro*", "openai/gpt-5*pro*"],
+      "gpt-5.1": ["copilot/gpt-5.1*", "openai/gpt-5.1*"],
+      "gpt-5.2": ["copilot/gpt-5.2*", "openai/gpt-5.2*"],
+      "gpt-5.3": ["copilot/gpt-5.3*", "openai/gpt-5.3*"],
+      "gpt-5.4": ["copilot/gpt-5.4*", "openai/gpt-5.4*"],
+      "gpt-5.5": ["copilot/gpt-5.5*", "openai/gpt-5.5*"],
+      "gpt-5.6": ["copilot/gpt-5.6*", "openai/gpt-5.6*"],
+      "gpt-6": ["copilot/gpt-6*", "openai/gpt-6*"],
+      "grok": ["copilot/*grok*", "openai/*grok*"],
+      "haiku": ["copilot/*haiku*", "anthropic/*haiku*"],
+      "image-generation": ["copilot/gpt-image*", "openai/gpt-image*", "openai/chatgpt-image*", "copilot/gemini-*image*", "google/gemini-*image*", "gemini/gemini-*image*", "google/imagen*"],
+      "kimi": ["copilot/kimi*", "openai/kimi*"],
+      "kiwi": ["copilot/kiwi*", "openai/kiwi*"],
+      "large": ["sonnet", "gpt-6", "gpt-5-pro", "gpt-5", "gemini-pro"],
+      "lyria": ["google/lyria*", "gemini/lyria*", "copilot/lyria*"],
+      "mai-code": ["copilot/MAI-Code*", "copilot/mai-code*", "openai/MAI-Code*"],
+      "mini": ["haiku", "gpt-5-mini", "gpt-5-nano", "gemini-flash-lite"],
+      "nano-banana": ["copilot/nano-banana*", "google/nano-banana*", "gemini/nano-banana*"],
+      "opus": ["copilot/*opus*", "anthropic/*opus*"],
+      "opusplan": ["opus?effort=high"],
+      "raptor-mini": ["copilot/raptor*", "openai/raptor*"],
+      "reasoning": ["copilot/o1*", "copilot/o3*", "copilot/o4*", "openai/o1*", "openai/o3*", "openai/o4*"],
+      "robotics": ["copilot/*robotics*", "google/*robotics*", "gemini/*robotics*"],
+      "small": ["mini"],
+      "small-agent": ["haiku", "gpt-5-mini", "gemini-flash"],
+      "sonnet": ["copilot/*sonnet*", "anthropic/*sonnet*"],
+      "sonnet-6x": ["copilot/*sonnet-4.5*", "copilot/*sonnet-4.6*", "copilot/*sonnet-5*", "copilot/*sonnet-4-5-*", "anthropic/*sonnet-4-5-*", "copilot/*sonnet-4-6*", "anthropic/*sonnet-4-6*", "anthropic/*sonnet-5*"],
+      "summarization": ["haiku", "gpt-5-mini", "gemini-flash-lite", "mini"],
+      "veo": ["google/veo*", "gemini/veo*"],
+      "vision": ["copilot/gemini-*image*", "google/gemini-*image*", "gemini/gemini-*image*", "copilot/gemini-*flash*", "google/gemini-*flash*", "gemini/gemini-*flash*"]
+    }
+  }
+}