fix(config): isolate plugin list reads from a broken JSONC layer

Plugin listing still called readConfigFile per layer, so one unparseable
project file made GET /api/config/plugins and VS Code listPluginEntries
fail. Reuse readConfigLayer isolation and pin comment-only empty parse
in the VS Code suite.

Co-authored-by: serkraser <serkraser@gmail.com>

packages/vscode/src/DOCUMENTATION.md

@@ -58,7 +58,7 @@ The webview CSP permits `blob:` only for `worker-src` so shared UI parsers can r
 - `bridge-config-runtime.ts`
   - Config and skills message handlers (`api:config/*`).
   - Includes OpenCode resolution diagnostics parity handler used by shared UI (`/api/config/opencode-resolution`).
-  - OpenCode JSONC reads in `opencodeConfig.ts` fail closed on a partial or non-object `jsonc-parser` tree (`INVALID_JSONC`) so mutations cannot rewrite a `$schema`-only stub over an existing config. Comment-only files read as empty. A broken layer is omitted from the merge and recorded on `layerErrors`; valid sibling layers still load, and writes still refuse to overwrite the broken file.
+  - OpenCode JSONC reads in `opencodeConfig.ts` fail closed on a partial or non-object `jsonc-parser` tree (`INVALID_JSONC`) so mutations cannot rewrite a `$schema`-only stub over an existing config. Comment-only files read as empty. A broken layer is omitted from the merge and recorded on `layerErrors`; valid sibling layers still load, including plugin list/read via `getPluginConfigSources`. Writes still refuse to overwrite the broken file.
 
 - `bridge-settings-runtime.ts`
   - Settings read/write and OpenCode skills discovery via API for bridge consumers.

packages/vscode/src/opencodeConfig.config-parse.test.ts

@@ -4,7 +4,7 @@ import fs from 'node:fs';
 import os from 'node:os';
 import path from 'node:path';
 
-import { updateMcpConfig } from './opencodeConfig';
+import { listPluginEntries, updateMcpConfig } from './opencodeConfig';
 
 const PARTIAL_PARSE_CONFIG = [
   '{',
@@ -94,6 +94,29 @@ describe('opencodeConfig JSONC parse safety (issue #2923)', () => {
     assert.equal(fs.readFileSync(`${configPath}.openchamber.backup`, 'utf8'), VALID_CONFIG);
   });
 
+  test('returns an empty object for a comment-only config file', () => {
+    const configPath = path.join(tempDir, 'comments.jsonc');
+    fs.writeFileSync(configPath, '// placeholder\n/* still empty */\n', 'utf8');
+    process.env.OPENCODE_CONFIG = configPath;
+
+    assert.deepEqual(listPluginEntries(), []);
+  });
+
+  test('lists custom-layer plugins when a project layer is unparseable', () => {
+    const customPath = path.join(tempDir, 'custom.jsonc');
+    const projectDir = path.join(tempDir, 'project');
+    const projectFile = path.join(projectDir, '.opencode', 'opencode.jsonc');
+    fs.writeFileSync(customPath, VALID_CONFIG, 'utf8');
+    fs.mkdirSync(path.dirname(projectFile), { recursive: true });
+    fs.writeFileSync(projectFile, PARTIAL_PARSE_CONFIG, 'utf8');
+    process.env.OPENCODE_CONFIG = customPath;
+
+    const specs = listPluginEntries(projectDir).map((entry) => entry.spec);
+    assert.deepEqual(specs, ['opencode-see-image']);
+    assert.equal(fs.readFileSync(projectFile, 'utf8'), PARTIAL_PARSE_CONFIG);
+    assert.equal(fs.existsSync(`${projectFile}.openchamber.backup`), false);
+  });
+
   test('keeps a valid custom layer writable when a project layer is unparseable', () => {
     const customPath = path.join(tempDir, 'custom.jsonc');
     const projectDir = path.join(tempDir, 'project');

packages/vscode/src/opencodeConfig.ts

@@ -926,10 +926,10 @@ const getPluginConfigSources = (workingDirectory?: string | null): Array<{ scope
   const projectPath = getProjectConfigPath(workingDirectory || undefined);
   return [
     customPath
-      ? { scope: 'user', path: customPath, config: readConfigFile(customPath) }
-      : { scope: 'user', path: userPath, config: readConfigFile(userPath) },
+      ? { scope: 'user', path: customPath, config: readConfigLayer(customPath).config }
+      : { scope: 'user', path: userPath, config: readConfigLayer(userPath).config },
     ...(projectPath
-      ? [{ scope: 'project' as const, path: projectPath, config: readConfigFile(projectPath) }]
+      ? [{ scope: 'project' as const, path: projectPath, config: readConfigLayer(projectPath).config }]
       : []),
   ];
 };