Merge pull request #728: fix: read a remote session's @fix_plan.md on its host, refuse remote Ralph writes

docs/architecture-invariants.md

@@ -87,7 +87,7 @@ Further detail: ⚠️ **Auto-reconnect revives ONLY when the durable remote tmu
 
 **Remote host wake-on-LAN from user input**: an optional `RemoteHost.wakeMac` (magic packet built and broadcast by Codeman) or `RemoteHost.wakeCommand` (a single executable path, run WITHOUT a shell, and the explicit override) lets the input route — and an explicit `POST /api/sessions/:id/wake` — wake a SLEEPING host instead of writing into a stalled ssh pane; `tmux send-keys` succeeds against a stalled pane, so the bytes used to vanish silently. The wake flow lives in `src/remote-wake.ts` and is reachable **only** from an EXPLICIT user request: `POST /api/sessions/:id/input`, that explicit wake route, and the create/attach path (`POST /api/quick-start` for a remote case, `POST /api/sessions` with `attachRemoteSession`, via `ensureHostAwake`), because "the user pressed Run on a sleeping host" is the same kind of request and the tmux probe would otherwise fail with a misleading "needs tmux installed". Everything TIMER-driven must never wake a host: the COD-108 auto-reconnect watcher, `Server.handleRemoteSessionDropped` and boot recovery have no access to the registry, or a host would be re-woken seconds after each suspend and could never stay asleep (asserted by wiring guards in `test/remote-wake.test.ts`, not just documented — including that `ensureHostAwake` is called from the HTTP route only, since `cron-service.ts` builds sessions through the shared service with nobody waiting on the answer). `GET /api/sessions/:id/reachability` only ASKS — it never wakes — and feeds the amber "host unreachable" banner (`host-wake-ui.js`) whose action is either Wake or, with no target configured, "Configure WoL" → `#wakeConfigModal` (saved via `PUT /api/remote-hosts/:id`). Detection is a throttled bare TCP probe (no ssh, no `ServerAliveInterval` — keepalives would move bytes into an idle connection every interval; and a host behind a jump host/SOCKS proxy is reachability-UNKNOWN, never "asleep": `isProbeable()` keeps the registry from buffering, gating or bannering on a probe that cannot reach it), input is buffered and flushed in order after `reattachRemote()` (the send-and-wait path blocks instead, as does the create path, with a shorter request budget), and the wake fields are re-read from `remote-hosts.json` on recovery AND (throttled, cached) live for a running session, because the persisted `remote` snapshot would never see a field added later (`rehydrateRemoteHostFields` + `RemoteWakeDeps.resolveRemote`). Design + invariants: `docs/remote-sessions.md` §Wake-on-LAN from user input.
 
-**Remote SSH cases** (COD-94/#145): cases can point at a **remote host** (`~/.codeman/remote-hosts.json` + `remote-cases.json` via `src/remote-hosts.ts`; CRUD under `/api/cases` — cases route file). A remote session launches a LOCAL tmux pane running `ssh <host>` that creates a durable REMOTE tmux session on a **dedicated socket** `-L codeman-remote` with name `codeman-ssh-<id>` — deliberately failing the remote Codeman's `SAFE_MUX_NAME_PATTERN` so a Codeman instance on the target host never adopts it; no `-g` global tmux options are set remotely. `remotePath`/`identityFile` are schema-guarded against shell injection (backticks/`$` rejected — same approach as `extraSshOptions`); remote tmux availability is probed via `checkRemoteTmuxAvailable()` in quick-start (ssh args carry `-o ConnectTimeout=10`). Remote claude defaults to an idempotent `claude --session-id <id> || claude --resume <id>` pair under a login shell, so a respawn or reattach continues the SAME conversation rather than starting a fresh one (remote omp gets the same treatment via `--continue`; ⚠️ because the claude arm is an `a || b` pair under `-c`, that pane's PID is the login shell, not the agent); per-host `commands.*` override. Session kill best-effort kills the remote tmux too. `SessionState.remote`/`MuxSession.remote` round-trip through recovery (`restoreMuxSessions` passes `remote` back into the Session constructor). ⚠️ Run flows must route remote cases through `POST /api/quick-start` (which resolves the remote case and skips LOCAL CLI availability gates) — `POST /api/sessions` stat-validates `workingDir` locally and has no `caseName`. `envOverrides`/`effort`/`modelOverride`/`codexConfig`/`geminiConfig` are rejected for remote quick-starts (not silently dropped). UI: Create Case modal → Remote tab. Tests: `test/remote-hosts.test.ts`, `test/remote-ssh-options.test.ts`. ⚠️ **Reading a file in a remote case goes over ssh too** (#415): `src/remote-files.ts` is the single remote-READ layer (`buildRemoteFileCommand` = `buildSshConnectionArgs` + one shellescaped remote command; `remoteProbePaths` returns remote realpath + stat; `remoteCreateReadStream` streams a `Range` via `tail -c +N | head -c L` and its `close()` must be wired to the response's `close` or the ssh child outlives an aborted download). The guard order matches the local path exactly (`validateSessionFilePathLexical` → remote realpath of BOTH file and workspace root → containment → sensitive-path → size cap on the REMOTE size), a request path arrives from the browser and is only ever interpolated as a `shellescape`d token, and an unreachable host answers **502**, never a 404. ⚠️ The probe's symlink resolution FAILS CLOSED: `readlink -f` where it exists, otherwise a `cd -P`/`pwd -P` directory walk plus a bounded plain-`readlink` loop over the last component, and anything it cannot fully resolve is reported unresolvable (404), never as the unresolved string — the first version resolved the directory chain only, so on a host without `readlink -f` a `ws/notes.txt -> ~/.ssh/id_rsa` link passed containment under its own path while `cat` served the key. Records are NUL-separated and index-keyed so a newline in a filename cannot shift the mapping. ⚠️ ssh children are BOUNDED: probes and buffered reads go through `src/remote-ssh-limiter.ts` (a `document-conversion-limiter`-shaped semaphore, default 4), the attachment-history list probes its whole history in ONE batched call (`probeRemoteAttachmentHistory`, threaded into `registerExternalAttachment({remoteProbes})`), and probes chunk at 40 paths — a prompt-injected agent printing `codeman://attach` links in a remote session used to fork one `ssh` per link. `describeExecError` never returns Node's `Command failed: <ssh line>` message (identity path + probe script in a 502 body). The `PUT /file-content` guard sits AHEAD of `validateSessionFilePath`, which resolves LOCALLY, or a same-named local directory (an sshfs mount) takes the write. Under `VITEST` the three IO functions refuse rather than connect. This covers the ATTACHMENT routes too, which is the half a clicked path needs when the file is OUTSIDE the case directory (`_isExternalPreviewPath` sends it to `POST …/attachments`): registration, by-id `raw`, metadata and the history list all resolve over ssh (`registerExternalAttachment({remote})`, `resolveServableRemoteAttachment`), and what decides the host is the SESSION, never the path string — the same absolute path means a different file on each host. Deliberately NOT supported over ssh: writes (`edit=1`/`PUT` answer 400, `editable` is always false), office previews/thumbnails, the file tree/picker, `tail-file`. Tests: `test/remote-files.test.ts`, `test/routes/file-routes-remote.test.ts`.
+**Remote SSH cases** (COD-94/#145): cases can point at a **remote host** (`~/.codeman/remote-hosts.json` + `remote-cases.json` via `src/remote-hosts.ts`; CRUD under `/api/cases` — cases route file). A remote session launches a LOCAL tmux pane running `ssh <host>` that creates a durable REMOTE tmux session on a **dedicated socket** `-L codeman-remote` with name `codeman-ssh-<id>` — deliberately failing the remote Codeman's `SAFE_MUX_NAME_PATTERN` so a Codeman instance on the target host never adopts it; no `-g` global tmux options are set remotely. `remotePath`/`identityFile` are schema-guarded against shell injection (backticks/`$` rejected — same approach as `extraSshOptions`); remote tmux availability is probed via `checkRemoteTmuxAvailable()` in quick-start (ssh args carry `-o ConnectTimeout=10`). Remote claude defaults to an idempotent `claude --session-id <id> || claude --resume <id>` pair under a login shell, so a respawn or reattach continues the SAME conversation rather than starting a fresh one (remote omp gets the same treatment via `--continue`; ⚠️ because the claude arm is an `a || b` pair under `-c`, that pane's PID is the login shell, not the agent); per-host `commands.*` override. Session kill best-effort kills the remote tmux too. `SessionState.remote`/`MuxSession.remote` round-trip through recovery (`restoreMuxSessions` passes `remote` back into the Session constructor). ⚠️ Run flows must route remote cases through `POST /api/quick-start` (which resolves the remote case and skips LOCAL CLI availability gates) — `POST /api/sessions` stat-validates `workingDir` locally and has no `caseName`. `envOverrides`/`effort`/`modelOverride`/`codexConfig`/`geminiConfig` are rejected for remote quick-starts (not silently dropped). UI: Create Case modal → Remote tab. Tests: `test/remote-hosts.test.ts`, `test/remote-ssh-options.test.ts`. ⚠️ **Reading a file in a remote case goes over ssh too** (#415): `src/remote-files.ts` is the single remote-READ layer (`buildRemoteFileCommand` = `buildSshConnectionArgs` + one shellescaped remote command; `remoteProbePaths` returns remote realpath + stat; `remoteCreateReadStream` streams a `Range` via `tail -c +N | head -c L` and its `close()` must be wired to the response's `close` or the ssh child outlives an aborted download). The guard order matches the local path exactly (`validateSessionFilePathLexical` → remote realpath of BOTH file and workspace root → containment → sensitive-path → size cap on the REMOTE size), a request path arrives from the browser and is only ever interpolated as a `shellescape`d token, and an unreachable host answers **502**, never a 404. ⚠️ The probe's symlink resolution FAILS CLOSED: `readlink -f` where it exists, otherwise a `cd -P`/`pwd -P` directory walk plus a bounded plain-`readlink` loop over the last component, and anything it cannot fully resolve is reported unresolvable (404), never as the unresolved string — the first version resolved the directory chain only, so on a host without `readlink -f` a `ws/notes.txt -> ~/.ssh/id_rsa` link passed containment under its own path while `cat` served the key. Records are NUL-separated and index-keyed so a newline in a filename cannot shift the mapping. ⚠️ ssh children are BOUNDED: probes and buffered reads go through `src/remote-ssh-limiter.ts` (a `document-conversion-limiter`-shaped semaphore, default 4), the attachment-history list probes its whole history in ONE batched call (`probeRemoteAttachmentHistory`, threaded into `registerExternalAttachment({remoteProbes})`), and probes chunk at 40 paths — a prompt-injected agent printing `codeman://attach` links in a remote session used to fork one `ssh` per link. `describeExecError` never returns Node's `Command failed: <ssh line>` message (identity path + probe script in a 502 body). The `PUT /file-content` guard sits AHEAD of `validateSessionFilePath`, which resolves LOCALLY, or a same-named local directory (an sshfs mount) takes the write. Under `VITEST` the three IO functions refuse rather than connect. This covers the ATTACHMENT routes too, which is the half a clicked path needs when the file is OUTSIDE the case directory (`_isExternalPreviewPath` sends it to `POST …/attachments`): registration, by-id `raw`, metadata and the history list all resolve over ssh (`registerExternalAttachment({remote})`, `resolveServableRemoteAttachment`), and what decides the host is the SESSION, never the path string — the same absolute path means a different file on each host. Deliberately NOT supported over ssh: writes (`edit=1`/`PUT` answer 400, `editable` is always false), office previews/thumbnails, the file tree/picker, `tail-file`. The Ralph file routes follow the same rules (`ralph-routes.ts`): `POST .../fix-plan/read` reads `@fix_plan.md` on the remote host through `remote-files.ts` (one probe of the file and the workspace, confined with the shared `isPathWithinRoot`, capped at 1 MB; missing or outside theLine truncated
 
 **Remote tmux PATH**: every SSH command that invokes or locates tmux uses `withRemoteTmuxPath()` (`remote-hosts.ts`) before the complete remote script is shell-escaped: link preflight, launch/attach, alive probes, discovery, history/screen capture, and cleanup. Non-interactive SSH shells can omit Homebrew and per-user binaries even when the user's interactive shell finds them. The wrapper double-quotes the exported PATH value (including inherited PATH) so homes with spaces work under dash; it leaves the existing SSH options, socket/target and inner CLI login-shell handling intact. tmux gives a new pane the PATH of the client that created it (measured on tmux 3.4), so every new remote pane, agent or shell, now starts on the widened PATH before its login shell runs. Keep new remote tmux operations on this same path. `test/remote-tmux-path.test.ts` exercises all builders under real sh/dash with a sparse PATH and a home containing spaces, using offline SSH/tmux stubs. Local and Docker tmux commands keep their own setup.
 

docs/remote-sessions.md

@@ -348,6 +348,8 @@ and it follows the same rule as the launch path: every ssh command line comes fr
 | `POST /api/sessions/:id/folders` | Lists a folder (absolute or `~/`) on the **remote** host in one ssh round trip (`remoteListFolder`): resolved with `cd -P`, missing → `404`, a file → `400 Not a folder` |
 | `GET /api/sessions/:id/folders/:folderId/files/:name/raw` | Streams one file of a granted remote folder over ssh after the same re-probe + guard as an attachment; `preview` (office) and `thumbnail` answer `400` |
 | `GET /api/sessions/:id/attachments/:attachmentId`, `GET …/attachments` (history) | Size/mtime/existence resolved over ssh, so a remote entry is not reported `missing`; the history list resolves EVERY entry in one batched probe, never one connection per entry |
+| `POST /api/sessions/:id/fix-plan/read` | Reads `@fix_plan.md` on the **remote** host (one probe of the file and the workspace, the same confinement, a 1 MB cap); missing or resolving outside the workspace → `NOT_FOUND`, not a regular file, over the cap or an ssh failure → `OPERATION_FAILED`; never a local fallback |
+| `POST /api/sessions/:id/fix-plan/write`, `POST /api/sessions/:id/ralph-prompt/write` | `400` (`INVALID_INPUT`) before any disk is touched: remote writes are out of scope, and a local write would land in a same-named local folder |
 
 ⚠️ The attachment route is the one a clicked path takes when it is **outside** the case
 directory (a remote `/tmp` scratchpad capture, a screenshot elsewhere in the home dir):