feat(web): the title bar is painted, a click survives an editor, and the twin door is gone

improvise-5jna, improvise-0x9u, improvise-seik — three browser-page defects with
one shape: a thing that looks done from every check except running it.

improvise-5jna. `doc_name`/`doc_dirty`/`doc_stored_as` were projected by z754 and
painted by nothing. `render_surface.test.js` could not see it — it is a SUBSTRING
SEARCH over the page's source, so a field named by a function nothing calls reads
as painted, which is also how `model.minibuffer` shipped dead. So the guard is a
harness assertion that loads the page and reads `#doc-name`, proved by writing it
first (`element(s) not found`). The joining is `shell.js::documentTitle`, the
TUI's own `name (stored_as) [+]` minus the chrome; the `[+]` is a node test, not a
harness one, because this deployment persists on every accepted batch and clears
the flag in the same round trip, so the marker is transient. UNPAINTED is now
empty.

improvise-0x9u. From an EDITING state a cell click did nothing at all: the
mousedown moved focus, the input's blur ran `close`, `close` repainted,
`replaceChildren` destroyed the `<td>` the mousedown landed on, and no `click`
was ever dispatched. The old spec pressed Escape between the two clicks, so it
only ever clicked from a non-editing page — this repo's characteristic defect.

Worth recording: moving to `mousedown` is NECESSARY AND NOT SUFFICIENT, and the
first attempt failed the same assertion with the same symptom. Removing a focused
`<input>` fires `blur` SYNCHRONOUSLY, so `close` rebuilt the table from inside
itself and detached the `<td>` again. `close` therefore no longer repaints, the
`blur` arm checks `closed` first, and the handler `preventDefault()`s so no focus
change happens at all — otherwise the default action focuses `#grid` after
`input.focus()` and blurs the new editor. `close` restores the DRAWN text, since
nothing repaints behind it any more.

improvise-seik. `Client::viewport` was a wasm-bindgen door with no caller, kept
for a reason `web/app.js` falsified in the same wave. It is one letter from
`set_viewport` and fails SILENTLY — identical frame, forgotten window, every
cursor key an upstream black hole. Deleted, along with the exported `init()` free
function that duplicated `new Client()`. The guard is not the deletion:
`wasm_surface.test.js` now reads the generated `.d.ts` and requires every
declared method to be one `app.js` calls or to be named in `UNCALLED` with its
reason. Proved by injecting a spare `static viewport(...)` into the built `.d.ts`
and watching it fail by name.

Tests: 1405 Rust (unchanged), 27 node + 4 bundle (was 26 + 3), 24 chromium
harness (was 23).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FC2jVn8Au7E9JPkw6bwXXH

web/app.js

@@ -7,6 +7,7 @@ import {
   HANDSHAKE_TIMEOUT_MS,
   ROW_PX,
   createShell,
+  documentTitle,
   extentOf,
   frameCostOf,
   gridPlan,
@@ -35,6 +36,7 @@ const el = {
   help: document.getElementById("help"),
   status: document.getElementById("status"),
   viewName: document.getElementById("view-name"),
+  docName: document.getElementById("doc-name"),
 };
 
 await init();
@@ -60,8 +62,8 @@ function sendViewport() {
   const box = el.grid.getBoundingClientRect();
   const metrics = { rowPx: ROW_PX, colPx: COL_PX };
   const { rows, cols } = extentOf(box, frameCost, metrics);
-  // `client.set_viewport`, NOT the associated `Client.viewport`: the same
-  // frame, but it also RECORDS the window. Why that matters: clients.md.
+  // `set_viewport` RECORDS the window as well as framing it; the frame-only
+  // twin beside it is deleted, so there is nothing to call by mistake (seik).
   transport.send(client.set_viewport(rows, cols));
 }
 
@@ -162,6 +164,13 @@ function repaint() {
   paintMinibuffer(model);
   shell.setModel(model.status);
   el.viewName.textContent = model.view_name;
+  // The title bar, off the cache `src/draw.rs::draw_title` folds — one
+  // derivation, both front ends (improvise-z754, improvise-5jna).
+  el.docName.textContent = documentTitle(
+    model.doc_name,
+    model.doc_dirty,
+    model.doc_stored_as,
+  );
   el.grid.replaceChildren(gridTable(model));
   // The flag is the client's answer, not the page's: `C` toggles it and the
   // TUI draws the panel on exactly the same condition (improvise-wsaw).
@@ -299,7 +308,12 @@ function gridTable(model) {
       // Every cell moves the selection; an editable one also opens its editor,
       // which is the pointer's `i`. Not repainted in that branch: `edit` has
       // set `editing`, and a repaint would take the <input> away.
-      td.addEventListener("click", () => {
+      // On MOUSEDOWN, and defaulted away: from an editing state the input's
+      // blur repainted first and this <td> was gone before `click` could fire
+      // (improvise-0x9u). See context/code/clients.md.
+      td.addEventListener("mousedown", (event) => {
+        event.preventDefault();
+        if (editing) editing.close(false);
         const frame = client.click_cell(cell.row, cell.col);
         if (frame) transport.send(frame);
         if (cell.editable) edit(td, cell.row, cell.col, cell.editText);
@@ -314,10 +328,12 @@ function gridTable(model) {
  *  back is the server's, never the string typed here. */
 function edit(td, row, col, seed) {
   if (editing) return;
-  editing = { row, col };
   // `seed` is `RenderCell::edit_text` -- the STORED value, not the drawn one:
   // `td.textContent` has been through the number format.
   const original = seed;
+  // What was on the screen, kept so closing can put it back: `close` no longer
+  // always repaints, so restoring `seed` would leave `1200` where `1,200` was.
+  const drawn = td.textContent;
   const input = document.createElement("input");
   input.value = original;
   td.replaceChildren(input);
@@ -327,6 +343,8 @@ function edit(td, row, col, seed) {
   // Enter removes the focused <input>, which fires `blur`, which calls
   // `close` again. Harmless before, but only by accident.
   let closed = false;
+  // `close` does NOT repaint: a caller about to open another editor on a live
+  // <td> must not have the table rebuilt under it (improvise-0x9u).
   const close = (commit) => {
     if (closed) return;
     closed = true;
@@ -337,19 +355,28 @@ function edit(td, row, col, seed) {
       // follows restores whatever the server now says is there.
       if (frame) transport.send(frame);
     }
-    td.replaceChildren(original);
+    td.replaceChildren(drawn);
     painted = -1;
+  };
+  const dismiss = (commit) => {
+    close(commit);
     repaint();
   };
+  editing = { row, col, close };
 
   input.addEventListener("keydown", (e) => {
-    if (e.key === "Enter") close(true);
-    else if (e.key === "Escape") close(false);
+    if (e.key === "Enter") dismiss(true);
+    else if (e.key === "Escape") dismiss(false);
     // The editor owns the keyboard while it is open; the page-level handler
     // below must not also see these.
     e.stopPropagation();
   });
-  input.addEventListener("blur", () => close(false));
+  // Removing the focused <input> fires `blur` SYNCHRONOUSLY, so a caller that
+  // already closed this editor must not have the table rebuilt from inside its
+  // own `close` — that is what detached the <td> in improvise-0x9u's repair.
+  input.addEventListener("blur", () => {
+    if (!closed) dismiss(false);
+  });
 }
 
 /** A side panel. An empty row list is what says it is closed — the page asks