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>

CLAUDE.md

@@ -245,6 +245,8 @@ Codeman is a Claude Code session manager with web interface and autonomous Ralph
 
 ⚠️ **llama-swap endpoints** (one model at a time): the apply routes check `GET /running` and return `requiresConfirmation` before evicting a model another live session uses; `confirmedSwap` and `confirmedContext` are SEPARATE flags and must stay so. Claude alone gets a context floor (`CLAUDE_MIN_SAFE_CONTEXT_TOKENS`); context is parsed from `/running`'s `cmd`, never trusted from `/props`. Backend log lines come from llama-swap's `/api/events` `upstream` source, never `/logs`. → [architecture-invariants#custom-model-endpoint-profiles](docs/architecture-invariants.md#custom-model-endpoint-profiles)
 
+**MCP server sync** (opt-in, `mcpSyncEnabled`, SYNCED, default OFF; `src/mcp-sync.ts`, `GET`/`POST /api/mcp-sync`): copies each installed, enabled CLI's user-level MCP servers into the others. It is the ONE subsystem that writes another CLI's REAL user config (`~/.claude.json`, `~/.codex/config.toml`, `~/.gemini/*`, opencode's), which is why it is opt-in and admin-only in multi-user mode (both verbs 403 for a non-admin, and the Settings group is hidden for them). Where each CLI keeps the file is registry data, `capabilities.mcpConfig` (`{ path, format, relocation? }`), never a branch on the id. ⚠️ ADDITIVE only: a name already defined, in any shape, is never edited or removed (a different same-name definition is a reported conflict), and a server switched off in its own CLI is never copied. ⚠️ Never write a file that did not parse; re-parse the NEW text and require every added server to read back before the tmp+rename (written through a symlink, previous file kept as `<file>.codeman-bak`, one apply at a time, else 409). ⚠️ A file that receives copied `env`/`headers` (secrets) is left `0600`, and so is the backup. ⚠️ Responses carry server NAMES only, never env values, headers or file text: a parse failure is reported by line and column (`describeMcpSyncError`), never the parser's own message (smol-toml and V8 both quote source). ⚠️ `mcpConfig.relocation` names the env var the CLI reads to move its file (`CLAUDE_CONFIG_DIR`, `CODEX_HOME`, `XDG_CONFIG_HOME`, `GEMINI_CLI_HOME`), resolved from the SERVER env at call time; a relative value reports the target `skipped`, never a guessed write, and a per-session `envOverrides` relocation is not followed. Tests must pass `home` (which drops the `process.env` default) or clear those vars first. → `docs/cli-registry.md` (MCP server sync), `docs/api-reference.md`, `docs/wiki/Settings-Reference.md`
+
 **Run launch synchronization**: the Run entrypoint holds an in-flight lock and disables `#runBtn` for the whole launch (≥500ms) so a double click cannot create duplicate `w<n>-<case>` sessions; `_ensureCreatedSessionVisible()` runs before `selectSession()` and `_onSessionCreated()` stays an idempotent upsert, so POST-first and SSE-first both render exactly one tab. ⚠️ **Closing has the mirror-image race**: `closeSession()` must read `wasActive` BEFORE its `await` and announce the delete via `_closingSessions`, and `_onSessionDeleted` skips the active-session handoff for ids in that set; never read `activeSessionId` after the fact. The fallback picks the first `sessionOrder` entry still in `sessions`. Tests: `test/session-close-fallback.test.ts`. → [architecture-invariants#run-launch-synchronization](docs/architecture-invariants.md#run-launch-synchronization)
 
 **Session lineage lines** (tab → tab it spawned, `sessionLineageLines`, per-device, desktop default ON): a create request may name its spawner via a `parentSessionId` body field or the `X-Codeman-Parent-Session` header; `resolveParentSessionId()` (route-helpers.ts) resolves it (exact id or unique ≥8-char prefix, live, visible, same owner) and ⚠️ anything unresolvable is DROPPED, never a 400. Rides `toState()`, no new SSE event. ⚠️ Rendering is a LAYER on the existing SVG pass (`_appendLineageConnectionLines` at the tail of `_updateConnectionLinesImmediate()`), geometry pure in `computeLineagePath()`: one U-bridge shape hanging from the strip bottom, colors keyed on the SPAWNING tab and memoized (never by draw index). ⚠️ Desktop only (z-index vs the fixed mobile header). ⚠️ Paths must keep `data-agent-id="lineage:<childId>"` (the entrance animation queries it); skip edges whose endpoint is scrolled out of the strip. → [architecture-invariants#session-lineage-lines-tab--tab-it-spawned](docs/architecture-invariants.md#session-lineage-lines-tab--tab-it-spawned)