fix(web): the bugs a chat that never closes for a turn exposes

An investigation pass over the client, driven by steering's new shape —
a composer that is always live makes adjacent latent bugs visible.

The event stream now watches for silence: the claw keeps the
connection alive with a comment every fifteen seconds, and three
missed ones abort the fetch and reconnect, so a half-open TCP after a
laptop sleep no longer reads as 'live' forever. A reconnect clears the
attempted-attachment set with the transcript, or an image whose fetch
failed during the outage never retries against the recovered stream.
Saving a token reloads the identity and accounts the 401 froze: the
banner cleared, but the pages stayed empty until a browser reload.

A failed POST retracts its optimistic sent row (and its pending echo,
so a message the claw did take still renders from the stream's echo);
before, a send into an unreachable claw left a phantom row waiting for
a reply that could never come. Drafts are per-session now — the
composer's text belonged to no session, so a draft typed into one
session sent into whichever was selected at Enter. The providers
login form distinguishes a landed login (the roster carries its id)
from a failed one and no longer closes on an unrelated state refresh.

Two cost fixes that read as jank on long turns: the streamed reply's
markdown re-parsed the whole text per delta (quadratic) and now
re-renders on a short trailing debounce; the attachment-image watcher
walked the whole transcript on every streamed chunk and now scans only
the items it has not seen. The accounts page drops a stray Rust-ism
comment, and the avatar row's meta line admits webp like its accept
attribute always did.

web/claw/app/app.vue

@@ -110,10 +110,16 @@ const attemptedAttachments = new Set<string>()
 // A replayed question's images fetch the same way — the stream carries
 // their attachment ids, never the bytes; locally sent rows hold their
 // own object URLs.
+//
+// The watch is deep (rows mutate in place as their bytes land), and it
+// fires on every streamed delta, so the scan covers only the items the
+// last pass did not see — the transcript only ever appends.
+let scannedItems = 0
+
 watch(
   transcriptItems,
   (items) => {
-    for (const item of items) {
+    for (const item of items.slice(scannedItems)) {
       if (item.kind === 'attachment') {
         const { id, media, url } = item.attachment
         if (media !== 'image' || url !== null || attemptedAttachments.has(id)) continue
@@ -134,6 +140,7 @@ watch(
         }
       }
     }
+    scannedItems = items.length
   },
   { deep: true },
 )
@@ -435,7 +442,7 @@ async function removeProvider(id: string): Promise<void> {
 async function send(message: { text: string; images: StagedImage[] }): Promise<void> {
   // The optimistic row renders the staged previews; the stream's
   // user_message echo carries the stored ids and dedupes against it.
-  transcript.addSent(
+  const rowId = transcript.addSent(
     message.text,
     message.images.map(({ media_type, url, name }) => ({ id: null, media_type, url, name })),
   )
@@ -451,6 +458,9 @@ async function send(message: { text: string; images: StagedImage[] }): Promise<v
     )
     apiError.value = null
   } catch (err) {
+    // The claw never took the message: retract the optimistic row, or
+    // it would sit there forever waiting for a reply that cannot come.
+    transcript.removeSent(rowId)
     noteApiError(err)
   } finally {
     busy.value = false
@@ -503,10 +513,14 @@ function saveToken(): void {
   authRequired.value = false
   apiError.value = null
   // The stream's retry loop reads the token fresh each attempt, so it
-  // recovers on its own; the polls below confirm the token works.
+  // recovers on its own; everything the 401 froze reloads now — the
+  // polls confirm the token works, and the identity and accounts pages
+  // were left empty by the failed fetches that raised the banner.
   void checkHealth()
   void refreshProviders()
   void refreshSessions()
+  void refreshIdentity()
+  void refreshAccounts()
 }
 
 // --- the one live subscription ---------------------------------------
@@ -524,8 +538,14 @@ function resubscribe(): void {
       streamStatus.value = status
       // A retry reopens the stream with the claw's replay of the
       // recorded turns: drop the mirror and let it rebuild, or the
-      // replay would double everything already on screen.
-      if (status === 'reconnecting') transcript.reset()
+      // replay would double everything already on screen. The
+      // attempted-attachment set goes too — a fetch that failed during
+      // the outage must retry against the recovered stream.
+      if (status === 'reconnecting') {
+        transcript.reset()
+        attemptedAttachments.clear()
+        scannedItems = 0
+      }
       if (status === 'open') void refreshSessions()
     },
     onNotice: pushNotice,