Show images in Files and add client_open to open files on a client Mac

docs/operations.md

@@ -371,11 +371,12 @@ Answers reach the agent as one message, listing each answer under the question i
 
 Task agents use the Macs the human has byre's app open on directly, with no approval, as they use the machine byre runs on. While it runs, the app (`mac/Sources/Byre/Remote.swift`, started with the global event stream and stopped with it) keeps a WebSocket open to `GET /api/clients/connect`, reconnecting 2s after it drops. The connection is keyed by its `Byre-Client` header and named by its `Byre-Host` header (both required); a newer connection with the same `Byre-Client` replaces the older one, while two apps open on one Mac each keep their own. The client tools take the host name, or the `id` from `list_clients`, which they need when more than one app is connected from that host (the call fails listing the ids). byre keeps the connections in memory (`internal/clients`), pinging each every 30s and dropping one that doesn't answer within 15s. The app pings too, every 10s, and reconnects when it has had no pong for 25s. That catches a socket byre dropped while the Mac slept: the close never reached the Mac, and without something sent on it the app would wait on it indefinitely. Over it byre sends `ClientRequest` text messages, each with a fresh `id`, and the app answers each with a `ClientReply` carrying that `id` (`error` when it couldn't carry it out), in any order, handling requests concurrently. A request whose client disconnects before replying fails with "<host> disconnected before replying".
 
-Implementer sessions get eight MCP tools for it (`internal/agents/clients.go`). The app sets its WebSocket's `maximumMessageSize` to 256 MiB, the same as byre's read limit, so file contents fit in one message each way.
+Implementer sessions get nine MCP tools for it (`internal/agents/clients.go`). The app sets its WebSocket's `maximumMessageSize` to 256 MiB, the same as byre's read limit, so file contents fit in one message each way.
 
 - `list_clients`: the status's `clients` (see "Status"), with each one's host, login, `id`, connection time, app commit and `last_action_at`; the most recently active is listed first and marked.
 - `client_bash`: `op: bash`. The app runs `/bin/zsh -l -c <command>` in the human's home directory through `Process`, which starts it in its own process group, stdin from `/dev/null` and stdout and stderr into one temporary file, and kills the group with `SIGKILL` after `timeout_ms` (default 120000, at most 600000), replying `exit_code` -1. Otherwise `exit_code` is the exit status, or 128 plus the signal. `output` is the file's last 64 KiB. The agent's call waits the timeout plus 30s for the reply. Background children the command leaves are not waited for or killed, and a command that quits the app keeps running.
 - `client_upload`: `op: upload`. `path` is checked against the worktree through an `os.Root`; byre registers a transfer naming the path's directory and base name under a random id for as long as the call waits (at most 10 minutes), and the app downloads `GET /api/clients/transfers/{transferId}`, which streams `tar -czf - -C <dir> -- <name>` (404 once the call has ended). The app unpacks it into a new `.byre-upload-<uuid>` directory beside `dest` (`~/` expanded, parent directories created), removes whatever is at `dest`, moves the archive's one entry there and removes the temporary directory.
+- `client_open`: a `client_upload` of `path` to `~/Library/Caches/byre/open/<random>/<path's base name>`, then an `op: bash` running `open` on it, so the file opens in that Mac's default app for its type. The folder is left in place for the human to keep or for macOS to clear.
 - `client_download`: `op: download`, the reverse. byre makes `dest`'s parent directories through an `os.Root` on the worktree and registers a receiving transfer (`Transfer.Receive`) for a fresh temporary directory; the app runs `tar -czf <temp file> -C <path's parent> -- <path's name>` and `PUT`s it to `/api/clients/transfers/{transferId}`, which writes it once (`O_EXCL`) and answers 204, and 404 for a sending transfer, one already received or one whose call has ended (`GET` likewise answers 404 for a receiving one). byre unpacks it into a new `.byre-download-<transfer id>` directory beside `dest`, removes whatever is at `dest`, renames the archive's one entry there and removes the temporary directories, all inside the `os.Root`.
 - `client_read`: `op: read_file`; the app replies with the file's bytes in `data`, reading on a detached task, off the main actor. It resolves symlinks, refuses anything but a regular file (a FIFO would block the open), and reads at most 64 MiB plus one byte, refusing a longer file, so the base64 reply stays well under byre's 256 MiB read limit, past which byre would drop the connection. A `.png`, `.jpg`, `.jpeg`, `.gif` or `.webp` path comes back as an image result; other files must be UTF-8 and come back as `cat -n` style numbered lines from `offset` (default 1) for `limit` lines (default 2000), with a closing line naming the next offset when lines remain.
 - `client_write`: `op: write_file` with `path` and `data`; on a detached task, off the main actor, the app resolves symlinks, refuses an existing path that isn't a regular file (a FIFO would block the write), creates the parent directories and writes the file in place (`Data.write` without `.atomic`), so an existing file keeps its permissions.
@@ -406,7 +407,7 @@ The Changes view lists the files with their counts, opens a file's diff on click
 
 The Files tab browses the selected task's worktree, read-only (`internal/server/files.go`). `GET /api/tasks/{taskId}/dir?path=` lists one directory, directories first and then by name, without entries named `.git`; `GET /api/tasks/{taskId}/file?path=` returns one regular file. Both take a slash-separated path relative to the worktree root and work only while the task is active (409 otherwise). Every path is opened through an `os.Root` on the worktree, so a path that leaves it, through `..`, an absolute path or a symlink at any depth, is a 400; a path with a `.git` component is also refused. A listing reports each entry as `dir`, `file` (with its size) or `other`, following symlinks that stay inside the worktree (`symlink` marks them); a symlink that leaves the worktree or points nowhere is `other` and can't be opened. Gitignored entries are listed with `ignored` set: one `git check-ignore --stdin` per listing (`git.Ignored`) over the entries' paths, taken from the directory's real path so a listing reached through an in-worktree symlink is checked where it really lives; untracked paths under an ignored directory count as ignored, tracked files never do. The view shows them dimmed with `ignored` beside them, and they open like anything else. A listing stops at `maxDirEntries` entries with `truncated` set. A file read sends at most `maxFileBytes`, cut back to a whole UTF-8 character, with `truncated` set when the file is longer; a file with a NUL byte or invalid UTF-8 in that part is `binary` and comes back with no text.
 
-The view shows a breadcrumb from `worktree` down to the current directory or file, the directory's entries (a `../` row to go up), or the file's text with line numbers and a note when only its start is shown. A file whose name ends in `.md` is rendered as Markdown with the transcript's renderer (`MarkdownView`) instead, with relative image paths taken from the file's own directory. Where you are is kept per task in memory (`Store.filePlaces`), so switching tasks or tabs returns to it, but a relaunch starts at the root. It refetches what it shows 1.5s after the selected task's last tool result or turn end, keeping the scroll position.
+The view shows a breadcrumb from `worktree` down to the current directory or file, the directory's entries (a `../` row to go up), or the file's text with line numbers and a note when only its start is shown. A file whose name ends in `.png`, `.jpg`, `.jpeg`, `.gif`, `.webp` or `.svg` is shown as an image, fetched whole from `GET /api/tasks/{taskId}/image` (see "Screenshots from implementers") again on each refetch, fitted to the pane width and opening full size on click. A file whose name ends in `.md` is rendered as Markdown with the transcript's renderer (`MarkdownView`) instead, with relative image paths taken from the file's own directory. Where you are is kept per task in memory (`Store.filePlaces`), so switching tasks or tabs returns to it, but a relaunch starts at the root. It refetches what it shows 1.5s after the selected task's last tool result or turn end, keeping the scroll position.
 
 Markdown rendered with a task (its transcript, questions, reviews, Markdown files in Files) links the worktree paths it mentions to Files (`InlineRenderer` in `mac/Sources/Byre/MarkdownView.swift`): a relative Markdown link (`[x](docs/a.md)`, from the file's own directory inside Files), a code span holding a path with a `/` that ends in a file name with an extension or in `/` (`` `mac/Sources/` ``), and the same kind of path in plain text, file names only. An absolute path counts when it starts with the task's worktree. A `:line`, `:line:col` or `#L12` suffix is dropped. The link is `byre-app://file?task=&path=`, which sets the task's place in Files to that file (or directory, for a trailing `/`) and focuses the task's Files tab. Nothing checks that the path exists; one that doesn't opens Files on its 404.