Daily use: attachments, edit and regenerate, the chat's menu, model avatars, a palette

- Attachments from the file dialog, a drop on the window (Rust holds the dropped paths; the page
  never names one) or a paste (the bytes as the raw body of the call), sent at once to
  /api/v2/attachments as multipart and shown above the composer.
- Edit message (rewind), Regenerate reply on the last reply, Copy on both.
- The chat's menu (header and a right click in the sidebar): rename, open in the web interface,
  archive, delete.
- The chat's model and effort in its header; effort for a new chat. Model avatars coloured as
  the server's stable_hue colours them (MD5 of the id, checked against Python), mixed into the
  theme's surface so no colour is hard-coded.
- Ctrl+K palette over commands and every chat's title; Ctrl+N, Ctrl+,.
- The agent's new states in the page; 34 new sentences in all eight languages, the server's own
  words where it has them; a Czech row that was Slovak; two untranslated strings.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

ui/js/models.js

@@ -0,0 +1,105 @@
+// Models as the person picks them: each with its avatar, as the server's web interface draws a
+// model without an uploaded image -- its initial on a colour of its own, the hue worked out from
+// the model's id exactly as the server does it (`stable_hue`: the first two bytes of the id's
+// MD5, modulo 360), so a model looks the same in the app and in the browser. Saturation and
+// lightness are the theme's (app.css), only the hue is the model's.
+
+import { h, icon, ICONS } from "./dom.js"
+import { menu } from "./popup.js"
+
+/** MD5 of a string's UTF-8 bytes (RFC 1321), as 16 bytes. For a colour, not for security. */
+function md5(text) {
+  const bytes = new TextEncoder().encode(text)
+  const S = [7, 12, 17, 22, 5, 9, 14, 20, 4, 11, 16, 23, 6, 10, 15, 21]
+  const K = Array.from({ length: 64 }, (_, i) => Math.floor(Math.abs(Math.sin(i + 1)) * 2 ** 32) >>> 0)
+  const len = bytes.length
+  const words = (((len + 8) >>> 6) + 1) * 16
+  const w = new Uint32Array(words)
+  for (let i = 0; i < len; i++) w[i >> 2] |= bytes[i] << ((i % 4) * 8)
+  w[len >> 2] |= 0x80 << ((len % 4) * 8)
+  w[words - 2] = (len * 8) >>> 0
+  w[words - 1] = Math.floor((len * 8) / 2 ** 32)
+  let a0 = 0x67452301
+  let b0 = 0xefcdab89
+  let c0 = 0x98badcfe
+  let d0 = 0x10325476
+  for (let off = 0; off < words; off += 16) {
+    let [A, B, C, D] = [a0, b0, c0, d0]
+    for (let i = 0; i < 64; i++) {
+      let F
+      let g
+      if (i < 16) [F, g] = [(B & C) | (~B & D), i]
+      else if (i < 32) [F, g] = [(D & B) | (~D & C), (5 * i + 1) % 16]
+      else if (i < 48) [F, g] = [B ^ C ^ D, (3 * i + 5) % 16]
+      else [F, g] = [C ^ (B | ~D), (7 * i) % 16]
+      F = (F + A + K[i] + w[off + g]) >>> 0
+      const s = S[(i >> 4) * 4 + (i % 4)]
+      A = D
+      D = C
+      C = B
+      B = (B + ((F << s) | (F >>> (32 - s)))) >>> 0
+    }
+    a0 = (a0 + A) >>> 0
+    b0 = (b0 + B) >>> 0
+    c0 = (c0 + C) >>> 0
+    d0 = (d0 + D) >>> 0
+  }
+  return [a0, b0, c0, d0].flatMap((v) => [v & 255, (v >>> 8) & 255, (v >>> 16) & 255, (v >>> 24) & 255])
+}
+
+/** The server's `stable_hue`: 0-359, the same for the same id everywhere. */
+export function stableHue(id) {
+  const d = md5(String(id))
+  return ((d[0] << 8) | d[1]) % 360
+}
+
+/** A model's avatar: its initial on its own colour. */
+export function avatar(model) {
+  const label = String(model?.name || model?.id || "?").trim() || "?"
+  const el = h("span", { class: "avatar", "aria-hidden": "true", text: label[0].toUpperCase() })
+  el.style.setProperty("--avatar-hue", String(stableHue(model?.id || label)))
+  return el
+}
+
+/**
+ * A model picker: a button showing the chosen model (avatar and name) that opens the list, each
+ * with its avatar. `onChange(id)` when another is chosen. The element's `value` is the id.
+ */
+export function modelPicker({ id, models, value, onChange, label }) {
+  let current = value
+  const btn = h("button", { type: "button", class: "picker", id, "aria-haspopup": "menu", "aria-label": label })
+  const draw = () => {
+    const m = models.find((x) => x.id === current)
+    btn.replaceChildren(
+      m ? avatar(m) : h("span", { class: "avatar avatar--none", "aria-hidden": "true" }),
+      h("span", { class: "picker__name", text: m ? m.name : current || "—" }),
+      icon(ICONS.chevronDown),
+    )
+    btn.title = m ? `${m.name} (${m.id})` : current || ""
+  }
+  btn.addEventListener("click", () => {
+    menu(
+      btn,
+      models.map((m) => ({
+        label: m.name,
+        lead: avatar(m),
+        checked: m.id === current,
+        run: () => {
+          if (m.id === current) return
+          current = m.id
+          draw()
+          onChange?.(m.id)
+        },
+      })),
+    )
+  })
+  Object.defineProperty(btn, "value", {
+    get: () => current,
+    set: (v) => {
+      current = v
+      draw()
+    },
+  })
+  draw()
+  return btn
+}