nit(#154): add t.Fatal guard if baseSubprocessArgs flag not found

Address sonnet NIT: if --repo or --pr is ever removed from
baseSubprocessArgs(), the mutation loop silently no-ops and the test
becomes meaningless. Adding a found guard and t.Fatal makes the
regression immediately visible.

cmd/review-bot/main_test.go

@@ -880,16 +880,9 @@ func TestMainSubprocess_MissingFlags(t *testing.T) {
 func TestMainSubprocess_InvalidReviewerName(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
-		os.Args = []string{"review-bot",
-			"--gitea-url", "http://localhost",
-			"--repo", "owner/repo",
-			"--pr", "1",
+		os.Args = append(baseSubprocessArgs(),
 			"--reviewer-name", "invalid name",
-			"--reviewer-token", "tok",
-			"--llm-base-url", "http://localhost",
-			"--llm-api-key", "key",
-			"--llm-model", "model",
-		}
+		)
 		main()
 		return
 	}
@@ -908,15 +901,20 @@ func TestMainSubprocess_InvalidReviewerName(t *testing.T) {
 func TestMainSubprocess_InvalidRepo(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
-		os.Args = []string{"review-bot",
-			"--gitea-url", "http://localhost",
-			"--repo", "invalidrepo",
-			"--pr", "1",
-			"--reviewer-token", "tok",
-			"--llm-base-url", "http://localhost",
-			"--llm-api-key", "key",
-			"--llm-model", "model",
+		args := baseSubprocessArgs()
+		// Replace the canonical --repo value with an invalid one.
+		found := false
+		for i, a := range args {
+			if a == "--repo" && i+1 < len(args) {
+				args[i+1] = "invalidrepo"
+				found = true
+				break
+			}
 		}
+		if !found {
+			t.Fatal("baseSubprocessArgs() does not contain --repo; test is broken")
+		}
+		os.Args = args
 		main()
 		return
 	}
@@ -935,15 +933,20 @@ func TestMainSubprocess_InvalidRepo(t *testing.T) {
 func TestMainSubprocess_InvalidPRNumber(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
-		os.Args = []string{"review-bot",
-			"--gitea-url", "http://localhost",
-			"--repo", "owner/repo",
-			"--pr", "notanumber",
-			"--reviewer-token", "tok",
-			"--llm-base-url", "http://localhost",
-			"--llm-api-key", "key",
-			"--llm-model", "model",
+		args := baseSubprocessArgs()
+		// Replace the canonical --pr value with a non-numeric string.
+		found := false
+		for i, a := range args {
+			if a == "--pr" && i+1 < len(args) {
+				args[i+1] = "notanumber"
+				found = true
+				break
+			}
 		}
+		if !found {
+			t.Fatal("baseSubprocessArgs() does not contain --pr; test is broken")
+		}
+		os.Args = args
 		main()
 		return
 	}
@@ -962,16 +965,9 @@ func TestMainSubprocess_InvalidPRNumber(t *testing.T) {
 func TestMainSubprocess_InvalidTemperature(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
-		os.Args = []string{"review-bot",
-			"--gitea-url", "http://localhost",
-			"--repo", "owner/repo",
-			"--pr", "1",
-			"--reviewer-token", "tok",
-			"--llm-base-url", "http://localhost",
-			"--llm-api-key", "key",
-			"--llm-model", "model",
+		os.Args = append(baseSubprocessArgs(),
 			"--llm-temperature", "5.0",
-		}
+		)
 		main()
 		return
 	}
@@ -990,16 +986,9 @@ func TestMainSubprocess_InvalidTemperature(t *testing.T) {
 func TestMainSubprocess_InvalidProvider(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
-		os.Args = []string{"review-bot",
-			"--gitea-url", "http://localhost",
-			"--repo", "owner/repo",
-			"--pr", "1",
-			"--reviewer-token", "tok",
-			"--llm-base-url", "http://localhost",
-			"--llm-api-key", "key",
-			"--llm-model", "model",
+		os.Args = append(baseSubprocessArgs(),
 			"--llm-provider", "invalid-provider",
-		}
+		)
 		main()
 		return
 	}
@@ -1015,6 +1004,25 @@ func TestMainSubprocess_InvalidProvider(t *testing.T) {
 	}
 }
 
+// baseSubprocessArgs returns the base set of required flags for subprocess tests
+// that need a fully-configured main() invocation. Each test appends its own
+// test-specific flags on top of this base.
+//
+// Using a helper here means that when the set of required flags changes, only
+// this function needs updating (instead of every test that passes all flags).
+func baseSubprocessArgs() []string {
+	return []string{
+		"review-bot",
+		"--vcs-url", "https://gitea.example.com",
+		"--repo", "owner/repo",
+		"--pr", "1",
+		"--reviewer-token", "tok",
+		"--llm-base-url", "https://api.example.com",
+		"--llm-api-key", "key",
+		"--llm-model", "gpt-4",
+	}
+}
+
 // cleanEnv returns environ without any GITEA/LLM/REVIEWER/VCS env vars that would
 // interfere with testing missing-flag scenarios.
 func cleanEnv() []string {
@@ -1389,13 +1397,14 @@ func TestFetchPatterns_MultipleRepos(t *testing.T) {
 func TestMainSubprocess_MissingLLMBaseURL(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
+		// Note: cannot use baseSubprocessArgs() here because --llm-base-url and
+		// --llm-api-key are intentionally omitted to test the missing-URL error.
 		os.Args = []string{"review-bot",
 			"--vcs-url", "https://gitea.example.com",
 			"--repo", "owner/repo",
 			"--pr", "1",
 			"--reviewer-token", "tok",
 			"--llm-model", "gpt-4",
-			// --llm-base-url and --llm-api-key intentionally omitted
 		}
 		main()
 		return
@@ -1417,6 +1426,8 @@ func TestMainSubprocess_MissingLLMBaseURL(t *testing.T) {
 func TestMainSubprocess_MissingAICoreCredentials(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
+		// Note: cannot use baseSubprocessArgs() here because aicore provider
+		// does not require --llm-base-url / --llm-api-key; those are omitted.
 		os.Args = []string{"review-bot",
 			"--vcs-url", "https://gitea.example.com",
 			"--repo", "owner/repo",
@@ -1446,17 +1457,10 @@ func TestMainSubprocess_MissingAICoreCredentials(t *testing.T) {
 func TestMainSubprocess_ConflictingPersonaFlags(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
-		os.Args = []string{"review-bot",
-			"--vcs-url", "https://gitea.example.com",
-			"--repo", "owner/repo",
-			"--pr", "1",
-			"--reviewer-token", "tok",
-			"--llm-base-url", "https://api.example.com",
-			"--llm-api-key", "key",
-			"--llm-model", "gpt-4",
+		os.Args = append(baseSubprocessArgs(),
 			"--persona", "security",
 			"--persona-file", "custom.json",
-		}
+		)
 		main()
 		return
 	}
@@ -1477,9 +1481,9 @@ func TestMainSubprocess_ConflictingPersonaFlags(t *testing.T) {
 func TestMainSubprocess_DeprecatedGiteaURLEnv(t *testing.T) {
 	if os.Getenv("TEST_SUBPROCESS_MAIN") == "1" {
 		flag.CommandLine = flag.NewFlagSet(os.Args[0], flag.ExitOnError)
-		// Set required flags but omit --vcs-url; GITEA_URL should be picked up.
-		// The test will exit with an error after VCS init (no PR to fetch), but
-		// the deprecation warning must appear.
+		// Note: cannot use baseSubprocessArgs() here because --vcs-url must be
+		// omitted — this test verifies that GITEA_URL env var is picked up as a
+		// deprecated fallback when --vcs-url is absent.
 		os.Args = []string{"review-bot",
 			// No --vcs-url: should fall back to GITEA_URL env var
 			"--repo", "owner/repo",