fix custom provider edit to preserve config scope

Derive the effective OpenCode config layer (custom > project > user) from
provider sources and send it on PUT /api/provider so project/custom edits
update that layer instead of creating a global user override. Resolve
OPENCODE_CONFIG at call time and add UI/web/VS Code coverage for scoped
upserts.

Co-authored-by: Serhii Dziupin <makeittech@users.noreply.github.com>

packages/vscode/src/DOCUMENTATION.md

@@ -61,7 +61,7 @@ The webview CSP permits `blob:` only for `worker-src` so shared UI parsers can r
   - Includes session activity snapshot bridge handler used by webview parity routes (`/api/session-activity`).
   - Includes Zen utility model parity handler used by shared notification settings (`/api/zen/models`).
   - Owns managed OpenCode upgrade status and mutation handlers, including capability reporting, upgrade serialization, and process restart after a successful upgrade.
-  - Provider handlers cover source lookup, disconnect (`DELETE /api/provider/:id/auth`), and custom provider upsert (`PUT /api/provider`; create/update OpenAI-compatible config; requires `env` or stored auth; secrets via OpenCode auth API).
+  - Provider handlers cover source lookup, disconnect (`DELETE /api/provider/:id/auth`), and custom provider upsert (`PUT /api/provider`; create/update OpenAI-compatible config with explicit `scope` for user/project/custom layers; requires `env` or stored auth; secrets via OpenCode auth API).
 
 - `opencode-upgrade-runtime.ts`
   - Owns managed-versus-external capability decisions, latest-version checks, serialized OpenCode self-upgrades, and restart-after-upgrade behavior.

packages/vscode/src/opencodeConfig.providers.test.ts

@@ -173,4 +173,93 @@ describe('custom provider config persistence (VS Code parity)', () => {
     assert.equal(result.providerId, 'keyed-provider');
     assert.equal(result.config.env, undefined);
   });
+
+  test('project-scope edit updates project layer without creating a user entry', () => {
+    const providerId = `proj-scope-${Date.now()}`;
+    const configPath = path.join(projectDir, 'opencode.json');
+
+    upsertProviderConfig(providerId, {
+      name: 'Project Scoped',
+      options: { baseURL: 'https://project.example.com/v1' },
+      models: { m: { name: 'M' } },
+    }, projectDir, 'project', { hasStoredAuth: true });
+
+    upsertProviderConfig(providerId, {
+      name: 'Project Scoped Updated',
+      options: { baseURL: 'https://project.example.com/v2', headers: { 'X-Project': '1' } },
+      models: { m: { name: 'M2' } },
+    }, projectDir, 'project', { hasStoredAuth: true });
+
+    const written = readJson(configPath);
+    assert.deepEqual(written.provider[providerId], {
+      npm: '@ai-sdk/openai-compatible',
+      name: 'Project Scoped Updated',
+      options: {
+        baseURL: 'https://project.example.com/v2',
+        headers: { 'X-Project': '1' },
+      },
+      models: { m: { name: 'M2' } },
+    });
+
+    const sources = getProviderSources(providerId, projectDir);
+    assert.equal(sources.project.exists, true);
+    assert.equal(sources.user.exists, false);
+    assert.equal(sources.custom.exists, false);
+
+    for (const userPath of [
+      path.join(os.homedir(), '.config', 'opencode', 'opencode.json'),
+      path.join(os.homedir(), '.config', 'opencode', 'config.json'),
+    ]) {
+      if (!fs.existsSync(userPath)) continue;
+      const userConfig = readJson(userPath);
+      assert.equal(userConfig.provider?.[providerId], undefined);
+      assert.equal(userConfig.providers?.[providerId], undefined);
+    }
+  });
+
+  test('custom-scope edit updates custom layer without creating a user entry', () => {
+    const providerId = `custom-scope-${Date.now()}`;
+    const customPath = path.join(projectDir, 'custom-opencode.json');
+    const previousEnv = process.env.OPENCODE_CONFIG;
+    process.env.OPENCODE_CONFIG = customPath;
+
+    try {
+      upsertProviderConfig(providerId, {
+        name: 'Custom Scoped',
+        options: { baseURL: 'https://custom.example.com/v1' },
+        models: { m: { name: 'M' } },
+      }, projectDir, 'custom', { hasStoredAuth: true });
+
+      upsertProviderConfig(providerId, {
+        name: 'Custom Scoped Updated',
+        options: { baseURL: 'https://custom.example.com/v2' },
+        models: { n: { name: 'N' } },
+      }, projectDir, 'custom', { hasStoredAuth: true });
+
+      const written = readJson(customPath);
+      assert.equal(written.provider[providerId].name, 'Custom Scoped Updated');
+      assert.equal(written.provider[providerId].options.baseURL, 'https://custom.example.com/v2');
+
+      const sources = getProviderSources(providerId, projectDir);
+      assert.equal(sources.custom.exists, true);
+      assert.equal(sources.user.exists, false);
+      assert.equal(sources.project.exists, false);
+
+      for (const userPath of [
+        path.join(os.homedir(), '.config', 'opencode', 'opencode.json'),
+        path.join(os.homedir(), '.config', 'opencode', 'config.json'),
+      ]) {
+        if (!fs.existsSync(userPath)) continue;
+        const userConfig = readJson(userPath);
+        assert.equal(userConfig.provider?.[providerId], undefined);
+        assert.equal(userConfig.providers?.[providerId], undefined);
+      }
+    } finally {
+      if (previousEnv === undefined) {
+        delete process.env.OPENCODE_CONFIG;
+      } else {
+        process.env.OPENCODE_CONFIG = previousEnv;
+      }
+    }
+  });
 });

packages/vscode/src/opencodeConfig.ts

@@ -10,9 +10,6 @@ const COMMAND_DIR = path.join(OPENCODE_CONFIG_DIR, 'commands');
 const GLOBAL_SNIPPET_DIR = path.join(OPENCODE_CONFIG_DIR, 'snippet');
 const GLOBAL_SNIPPET_DIR_ALT = path.join(OPENCODE_CONFIG_DIR, 'snippets');
 const CONFIG_FILE = path.join(OPENCODE_CONFIG_DIR, 'config.json');
-const CUSTOM_CONFIG_FILE = process.env.OPENCODE_CONFIG
-  ? path.resolve(process.env.OPENCODE_CONFIG)
-  : null;
 const PROMPT_FILE_PATTERN = /^\{file:(.+)\}$/i;
 const SNIPPET_EXTENSION = '.md';
 const SNIPPET_NAME_PATTERN = /^[a-z0-9][a-z0-9_-]{0,79}$/i;
@@ -541,7 +538,10 @@ const getConfigPaths = (workingDirectory?: string) => ({
     path.join(OPENCODE_CONFIG_DIR, 'opencode.jsonc'),
   ],
   projectPath: getProjectConfigPath(workingDirectory),
-  customPath: CUSTOM_CONFIG_FILE
+  // Resolve at call time so OPENCODE_CONFIG changes (and tests) take effect.
+  customPath: process.env.OPENCODE_CONFIG
+    ? path.resolve(process.env.OPENCODE_CONFIG)
+    : null,
 });
 
 const getPrimaryUserConfigPath = (userPaths: string[]): string => {