fix(coding-agent): handle invalid models json during migration

closes #5418

packages/coding-agent/CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### Fixed
 
+- Fixed invalid `models.json` syntax to skip startup config migrations and report the normal file-path-aware models error instead of a raw JSON parse stack trace ([#5418](https://github.com/earendil-works/pi/issues/5418)).
 - Fixed GitHub release notes and interactive changelog links to resolve package-relative documentation URLs correctly ([#5516](https://github.com/earendil-works/pi/issues/5516)).
 
 ## [0.79.0] - 2026-06-08

packages/coding-agent/src/migrations.ts

@@ -144,6 +144,7 @@ function migrateModelsJsonConfigValues(agentDir: string): ConfigValueMigration[]
 	const modelsPath = join(agentDir, "models.json");
 	if (!existsSync(modelsPath)) return [];
 
+	try {
 		const parsed = JSON.parse(stripJsonComments(readFileSync(modelsPath, "utf-8"))) as unknown;
 		if (typeof parsed !== "object" || parsed === null || Array.isArray(parsed)) return [];
 		const modelsData = parsed as Record<string, unknown>;
@@ -171,7 +172,8 @@ function migrateModelsJsonConfigValues(agentDir: string): ConfigValueMigration[]
 			const modelOverrides = providerRecord.modelOverrides;
 			if (typeof modelOverrides === "object" && modelOverrides !== null && !Array.isArray(modelOverrides)) {
 				for (const [modelId, modelOverride] of Object.entries(modelOverrides)) {
-				if (typeof modelOverride !== "object" || modelOverride === null || Array.isArray(modelOverride)) continue;
+					if (typeof modelOverride !== "object" || modelOverride === null || Array.isArray(modelOverride))
+						continue;
 					const modelOverrideRecord = modelOverride as Record<string, unknown>;
 					migrateHeadersConfig(
 						modelOverrideRecord.headers,
@@ -185,6 +187,9 @@ function migrateModelsJsonConfigValues(agentDir: string): ConfigValueMigration[]
 		if (migrations.length === 0) return [];
 		writeFileSync(modelsPath, `${JSON.stringify(parsed, null, 2)}\n`, "utf-8");
 		return migrations;
+	} catch {
+		return [];
+	}
 }
 
 function migrateExplicitEnvVarConfigValues(): void {

packages/coding-agent/test/config-value-migration.test.ts

@@ -3,6 +3,8 @@ import * as os from "node:os";
 import * as path from "node:path";
 import { afterEach, describe, expect, it, vi } from "vitest";
 import { ENV_AGENT_DIR } from "../src/config.ts";
+import { AuthStorage } from "../src/core/auth-storage.ts";
+import { ModelRegistry } from "../src/core/model-registry.ts";
 import { runMigrations } from "../src/migrations.ts";
 
 describe("config value env var syntax migration", () => {
@@ -68,6 +70,23 @@ describe("config value env var syntax migration", () => {
 		expect(logMessage).toContain('auth.json["anthropic"].key: ANTHROPIC_API_KEY -> $ANTHROPIC_API_KEY');
 	});
 
+	it.each([
+		["malformed", '{\n  "providers": {\n'],
+		["blank", ""],
+	])("does not throw on %s models.json during config migration", (_name, content) => {
+		const agentDir = createAgentDir();
+		const modelsPath = path.join(agentDir, "models.json");
+		fs.writeFileSync(modelsPath, content, "utf-8");
+
+		withAgentDir(agentDir, () => expect(() => runMigrations(agentDir)).not.toThrow());
+
+		expect(fs.readFileSync(modelsPath, "utf-8")).toBe(content);
+		const registry = ModelRegistry.create(AuthStorage.create(path.join(agentDir, "auth.json")), modelsPath);
+		const loadError = registry.getError();
+		expect(loadError).toContain("Failed to parse models.json");
+		expect(loadError).toContain(`File: ${modelsPath}`);
+	});
+
 	it("rewrites legacy uppercase models.json API key and header values", () => {
 		const agentDir = createAgentDir();
 		fs.writeFileSync(