fix(mcp): no file text in sync errors, follow relocated config dirs, docs and Settings polish (#521 review)

Maintainer merge-time fixes for the MCP server sync (opt-in mcpSyncEnabled, synced, default OFF).

M1, parse errors echoed config text (secrets included) into the HTTP response and Settings:
smol-toml's TomlError carries a code frame of the offending lines and V8's JSON "Unexpected
token" errors quote source. Both catch sites now go through describeMcpSyncError(): a parse
failure is reported by line/column only ("not valid TOML (line 3, column 21)", "not valid
JSON"), an errno failure by Node's own message (code, syscall, path), the module's own
messages via a McpConfigError class, anything else as "unexpected error". Tests put a secret
on the broken line (TOML, both JSON message shapes, and a write refused at the re-parse that
would have quoted a copied server's env) and assert it is absent from the result and from the
route's response body; they fail against the old code.

M2, CODEX_HOME / CLAUDE_CONFIG_DIR / XDG_CONFIG_HOME were ignored, so a sync could create a
file the CLI never reads and report success: new optional registry field
capabilities.mcpConfig.relocation { envVar, path } (registry data, no id branch; schema
reuses the env-name and no-traversal path rules). Declared for claude (CLAUDE_CONFIG_DIR,
checked in the 2.1.289 binary), codex (CODEX_HOME), opencode (XDG_CONFIG_HOME) and gemini
(GEMINI_CLI_HOME, gemini-cli paths.ts); antigravity follows $HOME only (agy 1.1.12 has no
relocation var). Resolved from the server process env at call time: absolute moves the file,
empty means unset, anything else reports the target with the new status "skipped" plus the
reason and writes nothing. Dedupe is now by resolved file. When a caller overrides `home`
without passing `env`, process.env is not consulted, and the route tests clear those vars so
a CI runner's XDG_CONFIG_HOME can never aim a write outside the temp HOME.

M3, feature undocumented: CLAUDE.md Key Patterns paragraph (opt-in, admin-only, additive
only, backups, re-parse validation, 0600 for copied secrets, names-only responses with
position-only parse errors, capabilities.mcpConfig and relocation), a Settings-Reference row
in the wiki, and docs/cli-registry.md + docs/api-reference.md updated for relocation, the
"skipped" status and the error policy.

Nits:
- N1 Preview/Sync before Save: the UI remembers the saved value on open and says "Save
  settings to turn MCP sync on first" instead of calling the routes; the 403 message also
  says to turn it on and save.
- N2 non-admins in multi-user mode: _applyMcpSyncAdminGate() hides the whole MCP group, called
  from applyMcpSyncVisibility() and the codeman:me event like the CLI-management gate.
- N3 scope chip says "synced".
- N4 "(1 servers)" pluralised; the unsupported list only names installed CLIs (route test
  pins it with a per-test installed set).
- N5 McpSyncResult / McpSyncTargetResult moved to src/types/mcp-sync.ts (barrel export); only
  the route imported them, so no churn.

Verified with an isolated instance (throwaway HOME, own instance and tmux socket) and
Playwright: chip, save-first message, preview rendering and the admin gate.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/web/public/settings-ui.js

@@ -417,7 +417,10 @@ Object.assign(CodemanApp.prototype, {
     // needs an explicit sync on every open, not just a save.
     this.applyCliManagementVisibility();
     // MCP server sync: synced, default OFF; same explicit-sync reasoning as above.
-    document.getElementById('appSettingsMcpSync').checked = settings.mcpSyncEnabled === true;
+    // The routes read the SAVED setting, so remember what it was on open: switching it on
+    // here does nothing server-side until Save (see mcpSync()).
+    this._mcpSyncSavedOn = settings.mcpSyncEnabled === true;
+    document.getElementById('appSettingsMcpSync').checked = this._mcpSyncSavedOn;
     this.applyMcpSyncVisibility();
     this.loadWebhook();
     // Read My Mind: synced, default OFF (opt-in; capture + prediction cost real tokens).
@@ -1173,6 +1176,20 @@ Object.assign(CodemanApp.prototype, {
     if (row) row.style.display = on ? '' : 'none';
     const out = this.$('mcpSyncResult');
     if (!on && out) { out.style.display = 'none'; out.innerHTML = ''; }
+    this._applyMcpSyncAdminGate();
+  },
+
+  /**
+   * Both /api/mcp-sync verbs are admin-only in multi-user mode (they write files in the server
+   * user's home), so a non-admin gets no MCP group at all, switch included, the same way
+   * _applyCliManagementAdminGate hides the CLI list. Also wired to `codeman:me`, because
+   * `window.__codemanUser`'s real role can resolve after settings were opened once.
+   */
+  _applyMcpSyncAdminGate() {
+    const group = document.getElementById('mcpSyncGroup');
+    if (!group) return;
+    const me = window.__codemanUser || {};
+    group.style.display = me.multiUser && me.role !== 'admin' ? 'none' : '';
   },
 
   /** Preview (apply=false) or run (apply=true) the MCP server sync across enabled CLIs. */
@@ -1181,6 +1198,11 @@ Object.assign(CodemanApp.prototype, {
     const show = (html) => {
       if (out) { out.style.display = 'block'; out.innerHTML = html; }
     };
+    // Switched on in this modal but not saved yet: the routes would only answer "disabled".
+    if (!this._mcpSyncSavedOn) {
+      show('Save settings to turn MCP sync on first, then reopen Settings to preview or sync.');
+      return;
+    }
     if (apply && !confirm('Add missing MCP servers to every installed, enabled CLI\'s config file? Env values and headers on those servers are copied too.')) return;
     show('Working…');
     const res = apply ? await this._apiPost('/api/mcp-sync', {}) : await this._api('/api/mcp-sync');
@@ -1193,12 +1215,14 @@ Object.assign(CodemanApp.prototype, {
     const data = body.data;
     const rows = data.targets.map((t) => {
       if (t.status === 'absent') return `<li><b>${escapeHtml(t.label)}</b>: not installed, skipped</li>`;
+      if (t.status === 'skipped') return `<li><b>${escapeHtml(t.label)}</b>: not touched (${escapeHtml(t.error || 'config location unknown')})</li>`;
       if (t.status === 'unreadable') return `<li><b>${escapeHtml(t.label)}</b>: not touched, file can't be read safely (${escapeHtml(t.error || 'unreadable')})</li>`;
       if (t.status === 'failed') return `<li><b>${escapeHtml(t.label)}</b>: failed (${escapeHtml(t.error || 'error')}); the file may be unchanged</li>`;
       const verb = data.applied ? 'added' : 'would add';
       const parts = [t.added.length ? `${verb} ${t.added.map(escapeHtml).join(', ')}` : 'up to date'];
       if (t.skipped.length) parts.push(`can't express ${t.skipped.map(escapeHtml).join(', ')}`);
-      return `<li><b>${escapeHtml(t.label)}</b> (${t.servers.length} servers): ${parts.join('; ')}</li>`;
+      const count = `${t.servers.length} server${t.servers.length === 1 ? '' : 's'}`;
+      return `<li><b>${escapeHtml(t.label)}</b> (${count}): ${parts.join('; ')}</li>`;
     });
     const conflicts = data.conflicts.length
       ? `<p>Defined differently across CLIs (each existing definition is kept; the first CLI's is copied where the name is missing): ${data.conflicts.map(escapeHtml).join(', ')}</p>`
@@ -4348,4 +4372,5 @@ Object.assign(CodemanApp.prototype, {
 document.addEventListener?.('codeman:me', () => {
   window.app?._applyCustomModelAdminGate?.();
   window.app?._applyCliManagementAdminGate?.();
+  window.app?._applyMcpSyncAdminGate?.();
 });