test: enhance llm error handling in cli tests

- Add tests for transient llm failures in git commit
- Implement retries for invalid llm JSON output

This update adds test cases to handle errors encountered with the LLM
during git commit operations, ensuring stability and reliability.

Co-Authored-By: Git Agent <noreply@git-agent.dev>

Author: xesrevinu

tests/cli-integration.test.ts

@@ -627,6 +627,100 @@ describe.concurrent("CLI integration", () => {
       }),
     );
 
+    it.effect(
+      "git commit retries transient llm failures in the http client layer",
+      Effect.fn(function* () {
+        const repo = yield* createGitRepo();
+        yield* writeTextFile(repo, "src/app.ts", "export const value = 'base';\n");
+        yield* gitCommitAll(repo, "chore: seed repo");
+        yield* writeTextFile(repo, "src/app.ts", "export const value = 'next';\n");
+        yield* gitCommitAll(repo, "feat(core): old message");
+
+        const llm = yield* startMockLlmServer([
+          {
+            status: 503,
+            content: {
+              error: {
+                message: "temporary upstream failure",
+              },
+            },
+          },
+          {
+            content: {
+              title: "fix(core): update app value",
+              bullets: ["Update app value output"],
+              explanation: "Updates the app value in the working tree.",
+            },
+          },
+        ]);
+
+        const result = yield* runCli(
+          [
+            "commit",
+            "--amend",
+            "--api-key",
+            "test-key",
+            "--base-url",
+            llm.baseUrl,
+            "--model",
+            "test-model",
+          ],
+          { cwd: repo },
+        );
+
+        expect(result.exitCode).toBe(0);
+        expect(llm.requests).toHaveLength(2);
+        expect((yield* git(repo, ["log", "-1", "--format=%s"])).stdout.trim()).toBe(
+          "fix(core): update app value",
+        );
+      }),
+    );
+
+    it.effect(
+      "git commit retries invalid llm json output",
+      Effect.fn(function* () {
+        const repo = yield* createGitRepo();
+        yield* writeTextFile(repo, "src/app.ts", "export const value = 'base';\n");
+        yield* gitCommitAll(repo, "chore: seed repo");
+        yield* writeTextFile(repo, "src/app.ts", "export const value = 'next';\n");
+        yield* gitCommitAll(repo, "feat(core): old message");
+
+        const llm = yield* startMockLlmServer([
+          {
+            content:
+              '{"title":"fix(core): update app value","bullets":["Update app value output"],"explanation":"Updates the app value"',
+          },
+          {
+            content: {
+              title: "fix(core): update app value",
+              bullets: ["Update app value output"],
+              explanation: "Updates the app value in the working tree.",
+            },
+          },
+        ]);
+
+        const result = yield* runCli(
+          [
+            "commit",
+            "--amend",
+            "--api-key",
+            "test-key",
+            "--base-url",
+            llm.baseUrl,
+            "--model",
+            "test-model",
+          ],
+          { cwd: repo },
+        );
+
+        expect(result.exitCode).toBe(0);
+        expect(llm.requests).toHaveLength(2);
+        expect((yield* git(repo, ["log", "-1", "--format=%s"])).stdout.trim()).toBe(
+          "fix(core): update app value",
+        );
+      }),
+    );
+
     it.effect(
       "git commit exits with hook-blocked status after repeated conventional hook failures",
 

tests/integration/helpers.ts

@@ -22,10 +22,12 @@ export interface MockLlmRequest {
 }
 
 export interface MockLlmResponse {
-  readonly content:
+  readonly content?:
     | string
     | Record<string, unknown>
     | ((request: MockLlmRequest) => string | Record<string, unknown>);
+  readonly headers?: Record<string, string>;
+  readonly status?: number;
 }
 
 export interface MockLlmServer {
@@ -203,12 +205,12 @@ export const runCli = (args: ReadonlyArray<string>, options: CliOptions) => {
     env: {
       PWD: options.cwd,
       XDG_CONFIG_HOME: isolatedConfigHome,
-      OPENAI_COMPACT_API_KEY: undefined,
-      OPENAI_COMPACT_API_BASE_URL: undefined,
-      OPENAI_COMPACT_MODEL: undefined,
-      GIT_AGENT_BUILD_API_KEY: undefined,
-      GIT_AGENT_BUILD_BASE_URL: undefined,
-      GIT_AGENT_BUILD_MODEL: undefined,
+      OPENAI_COMPACT_API_KEY: "",
+      OPENAI_COMPACT_API_BASE_URL: "",
+      OPENAI_COMPACT_MODEL: "",
+      GIT_AGENT_BUILD_API_KEY: "",
+      GIT_AGENT_BUILD_BASE_URL: "",
+      GIT_AGENT_BUILD_MODEL: "",
       ...options.env,
     },
   });
@@ -262,7 +264,21 @@ export const startMockLlmServer = (responses: ReadonlyArray<MockLlmResponse>) =>
 
         const content =
           typeof next.content === "function" ? next.content(requestInfo) : next.content;
-        response.writeHead(200, { "content-type": "application/json" });
+        const status = next.status ?? 200;
+        const headers = {
+          "content-type": "application/json",
+          ...next.headers,
+        };
+        if (status !== 200) {
+          response.writeHead(status, headers);
+          response.end(
+            typeof content === "string"
+              ? content
+              : JSON.stringify(content ?? { error: { message: "mock llm error" } }),
+          );
+          return;
+        }
+        response.writeHead(status, headers);
         const text = typeof content === "string" ? content : JSON.stringify(content);
         response.end(
           JSON.stringify({