fix(install): reject malformed empty-container JSONC commas

scripts/lib/install/hook-consent.js

@@ -92,6 +92,14 @@ function skipJsoncTrivia(input, start) {
   }
 }
 
+function isJsoncTrailingComma(input, index, previousSignificant) {
+  const next = skipJsoncTrivia(input, index + 1);
+  // Preserve commas in empty containers or after another separator so
+  // JSON.parse rejects them; it validates the remaining value syntax.
+  return (input[next] === '}' || input[next] === ']')
+    && previousSignificant !== null && !'[{,:'.includes(previousSignificant);
+}
+
 /**
  * Strip // and /* *\/ comments and the trailing commas they hide, without
  * touching string contents (URLs like "https://..." must survive intact).
@@ -100,6 +108,7 @@ function stripJsonc(input) {
   let out = '';
   let inString = false;
   let escaped = false;
+  let previousSignificant = null;
   for (let i = 0; i < input.length; i += 1) {
     const ch = input[i];
     if (inString) {
@@ -112,6 +121,7 @@ function stripJsonc(input) {
     if (ch === '"') {
       inString = true;
       out += ch;
+      previousSignificant = '"';
       continue;
     }
     if (ch === '/' && input[i + 1] === '/') {
@@ -128,12 +138,10 @@ function stripJsonc(input) {
       continue;
     }
     if (ch === ',') {
-      const next = skipJsoncTrivia(input, i + 1);
-      // A comma before '}' or ']' (ignoring trivia) is a trailing comma
-      // JSON forbids.
-      if (input[next] === '}' || input[next] === ']') continue;
+      if (isJsoncTrailingComma(input, i, previousSignificant)) continue;
     }
     out += ch;
+    if (!/\s/.test(ch)) previousSignificant = ch;
   }
   return out;
 }

tests/lib/opencode-hook-consent-safety.test.js

@@ -169,6 +169,15 @@ function runTests() {
     try { callback(); passed++; console.log(`  PASS ${name}`); }
     catch (error) { failed++; console.error(`  FAIL ${name}: ${error.stack}`); }
   };
+  test('JSONC rejects commas without a preceding value but keeps valid trailing commas', () => {
+    for (const content of ['{"plugin":[,]}', '{"plugin":[/* note */,]}', '{"plugin":[1,,]}', '{,}', '{"plugin":,}']) {
+      assert.throws(() => parseJsoncConfig(content, 'opencode.json'), /Failed to parse opencode\.json/);
+    }
+    assert.deepStrictEqual(
+      parseJsoncConfig('{"plugin":["user", /* note */],}', 'opencode.json').plugin,
+      ['user'],
+    );
+  });
   test('relative-root fixture remains relative across Windows checkout and temp drives', () => {
     const source = 'C:\\private\\source';
     assert.strictEqual(path.win32.isAbsolute(path.win32.relative('D:\\checkout', source)), true);
@@ -248,6 +257,21 @@ function runTests() {
       assert.strictEqual(fs.readFileSync(destination, 'utf8'), '{ malformed');
       assert.deepStrictEqual(fs.readFileSync(value.installStatePath), before);
     }));
+    test(`${mode} rejects an empty-array comma with source context`, () => fixture(value => {
+      const destination = path.join(value.targetRoot, 'opencode.json');
+      const content = '{"plugin":[,]}';
+      fs.writeFileSync(destination, content);
+      const before = fs.readFileSync(value.installStatePath);
+      if (mode === 'apply') assert.throws(() => applyInstallPlan(value.declinePlan), /Failed to parse .*opencode\.json/);
+      else if (mode === 'repair') assert.match(repair(value).results[0].error, /Failed to parse .*opencode\.json/);
+      else {
+        const result = buildDoctorReport({ repoRoot: value.sourceRoot, homeDir: value.homeDir,
+          projectRoot: value.homeDir, targets: ['opencode'] }).results[0];
+        assert.match(JSON.stringify(result.issues), /Failed to parse .*opencode\.json/);
+      }
+      assert.strictEqual(fs.readFileSync(destination, 'utf8'), content);
+      assert.deepStrictEqual(fs.readFileSync(value.installStatePath), before);
+    }));
     test(`${mode} reports a non-array plugin with source context`, () => fixture(value => {
       const destination = path.join(value.targetRoot, 'opencode.json');
       fs.writeFileSync(destination, '{"plugin":"./plugins"}');
@@ -375,6 +399,17 @@ function runTests() {
       assert.ok(result.skippedOperations.some(operation => operation.destinationPath === destination));
       assert.strictEqual(fs.existsSync(`${value.installStatePath}.ecc.lock`), false);
     }));
+    test(`fresh ${consent || 'default'} apply rejects malformed user JSONC without adopting it`, () => fixture(value => {
+      fs.unlinkSync(value.installStatePath);
+      fs.unlinkSync(path.join(value.targetRoot, 'plugins/ecc-hooks.ts'));
+      const destination = path.join(value.targetRoot, 'opencode.json');
+      const content = '{"plugin":[,]}';
+      fs.writeFileSync(destination, content);
+      assert.throws(() => applyInstallPlan(withHookConsent(value.basePlan, consent)), /Failed to parse .*opencode\.json/);
+      assert.strictEqual(fs.readFileSync(destination, 'utf8'), content);
+      assert.strictEqual(fs.existsSync(value.installStatePath), false);
+      assert.strictEqual(fs.existsSync(`${value.installStatePath}.ecc.lock`), false);
+    }));
     test(`fresh ${consent || 'default'} apply still refuses active unrecorded config`, () => fixture(value => {
       fs.unlinkSync(value.installStatePath);
       fs.unlinkSync(path.join(value.targetRoot, 'plugins/ecc-hooks.ts'));