fix(config): tolerate trailing commas in micode.json and warn on parse errors

src/config-loader.ts

@@ -6,6 +6,20 @@ import { join } from "node:path";
 
 import type { AgentConfig } from "@opencode-ai/sdk";
 
+import { log } from "./utils/logger";
+
+/**
+ * Strip trailing commas from JSON strings to be lenient with hand-edited configs.
+ * Matches quoted strings first (and keeps them intact) so that commas inside
+ * string values like "hello, }" are never modified.
+ */
+function stripTrailingCommas(json: string): string {
+  return json.replace(/"(?:[^"\\]|\\.)*"|,\s*([\]}])/g, (match, bracket) => {
+    if (bracket === undefined) return match;
+    return bracket;
+  });
+}
+
 // Minimal type for provider validation - only what we need
 export interface ProviderInfo {
   id: string;
@@ -30,7 +44,7 @@ function loadOpencodeConfig(configDir?: string): OpencodeConfig | null {
   try {
     const configPath = join(baseDir, "opencode.json");
     const content = readFileSync(configPath, "utf-8");
-    return JSON.parse(content) as OpencodeConfig;
+    return JSON.parse(stripTrailingCommas(content)) as OpencodeConfig;
   } catch {
     return null;
   }
@@ -98,9 +112,21 @@ export async function loadMicodeConfig(configDir?: string): Promise<MicodeConfig
   const baseDir = configDir ?? join(homedir(), ".config", "opencode");
   const configPath = join(baseDir, "micode.json");
 
+  let content: string;
   try {
-    const content = await readFile(configPath, "utf-8");
-    const parsed = JSON.parse(content) as Record<string, unknown>;
+    content = await readFile(configPath, "utf-8");
+  } catch (error: unknown) {
+    // File not found is expected and silent
+    if (error instanceof Error && "code" in error && (error as NodeJS.ErrnoException).code === "ENOENT") {
+      return null;
+    }
+    const message = error instanceof Error ? error.message : String(error);
+    log.warn("micode", `Failed to read micode.json: ${message}. Config overrides will be ignored.`);
+    return null;
+  }
+
+  try {
+    const parsed = JSON.parse(stripTrailingCommas(content)) as Record<string, unknown>;
 
     const result: MicodeConfig = {};
 
@@ -160,7 +186,10 @@ export async function loadMicodeConfig(configDir?: string): Promise<MicodeConfig
     }
 
     return result;
-  } catch {
+  } catch (error: unknown) {
+    // File exists but failed to parse - warn the user
+    const message = error instanceof Error ? error.message : String(error);
+    log.warn("micode", `Failed to parse micode.json: ${message}. Config overrides will be ignored.`);
     return null;
   }
 }
@@ -176,7 +205,7 @@ export function loadModelContextLimits(configDir?: string): Map<string, number>
   try {
     const configPath = join(baseDir, "opencode.json");
     const content = readFileSync(configPath, "utf-8");
-    const config = JSON.parse(content) as {
+    const config = JSON.parse(stripTrailingCommas(content)) as {
       provider?: Record<string, { models?: Record<string, { limit?: { context?: number } }> }>;
     };
 

tests/config-loader.test.ts

@@ -1,5 +1,5 @@
 // tests/config-loader.test.ts
-import { afterEach, beforeEach, describe, expect, it } from "bun:test";
+import { afterEach, beforeEach, describe, expect, it, spyOn } from "bun:test";
 import { mkdirSync, rmSync, writeFileSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
@@ -44,12 +44,61 @@ describe("config-loader", () => {
     expect(config?.agents?.brainstormer?.temperature).toBe(0.5);
   });
 
-  it("should return null for invalid JSON", async () => {
+  it("should return null and warn for invalid JSON", async () => {
     const configPath = join(testConfigDir, "micode.json");
-    writeFileSync(configPath, "{ invalid json }");
+    writeFileSync(configPath, '{ "agents": BROKEN }');
+
+    const warnSpy = spyOn(console, "warn").mockImplementation(() => {});
 
     const config = await loadMicodeConfig(testConfigDir);
+
     expect(config).toBeNull();
+    expect(warnSpy).toHaveBeenCalledWith(expect.stringContaining("Failed to parse micode.json"));
+
+    warnSpy.mockRestore();
+  });
+
+  it("should parse JSON with trailing commas", async () => {
+    const configPath = join(testConfigDir, "micode.json");
+    writeFileSync(
+      configPath,
+      `{
+        "agents": {
+          "commander": { "model": "openai/gpt-4o", },
+          "brainstormer": { "model": "anthropic/claude-opus-4-6", "temperature": 0.8, },
+        },
+        "compactionThreshold": 0.5,
+      }`,
+    );
+
+    const config = await loadMicodeConfig(testConfigDir);
+
+    expect(config).not.toBeNull();
+    expect(config?.agents?.commander?.model).toBe("openai/gpt-4o");
+    expect(config?.agents?.brainstormer?.model).toBe("anthropic/claude-opus-4-6");
+    expect(config?.agents?.brainstormer?.temperature).toBe(0.8);
+    expect(config?.compactionThreshold).toBe(0.5);
+  });
+
+  it("should not corrupt string values containing commas and brackets", async () => {
+    const configPath = join(testConfigDir, "micode.json");
+    writeFileSync(
+      configPath,
+      JSON.stringify({
+        fragments: {
+          brainstormer: ["hello, }", "keep this, ]too", 'escaped \\" comma, }'],
+        },
+      }),
+    );
+
+    const config = await loadMicodeConfig(testConfigDir);
+
+    expect(config).not.toBeNull();
+    expect(config?.fragments?.brainstormer).toEqual([
+      "hello, }",
+      "keep this, ]too",
+      'escaped \\" comma, }',
+    ]);
   });
 
   it("should handle empty agents object", async () => {