Build the Raw Source outlet

The escape hatch: View > Raw Source (opt-cmd-E) unmounts the whole
content area for the literal on-disk index.md in a plain monospaced
editor with Cancel/Apply. Raw source is window-level state, not a third
body mode — entry rides setMode(.preview), which flushes the Edit
session by construction, then reads the file fresh; exit reveals
Preview, and an empty body after Apply does not reopen Edit (openIfNeeded
already ran). Apply validates the proposed bytes through the loader's
own card checks — parseDocument's strict UTF-8/BOM rejection, schema,
order — deliberately skipping the uneditable-shape refusal, since a
flow-mapping card is exactly what the hatch repairs; invalid bytes
alert in place with the loader's own error and no bracket opens. The
write is byte-for-byte with no modified stamp and no modified-by clear,
per 01's explicit carve-out — the verbatim contract outranks stamping —
and identical bytes write nothing. Escape cancels, cmd-Return applies,
toggle-off applies too, and cmd-E disables while raw is active via a
testable predicate. Tombstoned targets refuse as vanished: a foreign
delete is never reverted by a stale buffer.

Claude-Session: https://claude.ai/code/session_01SR4XGjmBE16ZUYWpfFHXwY

README.md

@@ -36,6 +36,8 @@ Lanework is in early development. This list tracks what has actually shipped and
 
 - **The card body — Preview and Edit** — the body is read as a fully rendered Markdown preview and written as raw Markdown, never a WYSIWYG halfway house. Preview lays out headings, emphasis, code, quotes, lists, GFM tables, thematic breaks and images resolved against the card's own folder; HTML shows verbatim as code, remote images never load (Preview does no networking), links open in the browser or the file's default app, and task-list checkboxes are live — clicking one flips exactly that character in the file and touches no other byte. ⌘E toggles View ▸ Edit Body, Return in Preview enters it, Escape leaves it, and a card whose body is empty opens straight into the editor with the cursor ready. Edit is a monospaced editor with lightweight syntax highlighting — headings emphasized, bold and italic styled, code tinted, link targets and structural markers dimmed — that is presentation only: the text stays the raw Markdown character for character, smart quotes and dashes off. It saves ~700 ms after you stop typing, and flushes the moment you leave Edit or close the window, so neither the preview nor the disk ever lags what you typed. ⌘Z is the editor's own undo, scoped to the session; ⌘F is find-in-text over whichever surface is showing. Three write rules keep the file honest: a body nobody touched is never re-serialized (byte-identical on disk, modification date included), an edit typed and then undone is not written, and the app's own save echoing back through the watcher is not written again. If the file changes underneath you while the buffer has unsaved keystrokes, the buffer wins — the board, the preview and every other window take the new version while your text stays exactly where it is, and your save then lands over theirs. A close that cannot save stops and asks: try again, save a copy elsewhere, or discard.
 
+- **Raw source** — View ▸ Raw Source (⌥⌘E) swaps the card window's whole content area — title, body and sidebar — for the literal `index.md` in a monospaced editor with Cancel and Apply. It's the escape hatch that keeps everything reachable in-app: unknown keys an agent added, hand-written comments, exotic YAML the app has no control for. Entering flushes whatever you were typing and then reads the file fresh off disk, never an in-memory copy. Apply validates through the very same fail-fast parse the loader uses — a broken proposal stops with a detailed alert naming the line, source mode stays open with your text, and the file on disk is untouched — and a valid one is written byte for byte, the only write in the app that neither stamps `modified` nor clears a `modified-by` you typed or kept, because you wrote those bytes and nothing may quietly edit them. The reload then refreshes every window. Escape is Cancel, ⌘↩ is Apply, ⌥⌘E toggled off applies too, Return just types; Cancel and closing the window discard without ceremony, and a card deleted out from under an open buffer discards it rather than letting a stale Apply undelete the card. ⌘E stands down while source mode is up, ⌘F still finds, and ⌘Z is the editor's own undo. A file that isn't valid UTF-8 declines to open as source rather than showing you a lossy guess of it.
+
 - **The board popover** — a quiet chevron beside the window title (File ▸ Board Info, ⌘I, which toggles it) opens the board's one configuration surface. Renaming edits the board's frontmatter `title` and nothing else — the folder is never renamed, so the app's display name and the Finder document name are free to diverge — and clearing the field removes the key entirely, dropping the window title back to the folder name rather than to "Untitled"; the edit commits on Return and on click-away, Escape abandons it, and an unchanged title writes nothing at all. Below it sits the same style editor every other anchor uses, aimed permanently at the board, and below that a Git section that says plainly that this board has no repository yet. The read-only lock disables the surface without closing it.
 
 ## Development