feat(#17): web bind UI — plane selector + bound-state indicator (slice 3c UI)

Completes slice 3c: the browser-facing trigger for the web bind. A 'Bifrost
binding' <select> (none / memory / affect) on the setup panel; startSession
sends bifrost_plane in the create body (the consumer key stays server-held,
never sent from the browser). On a bound 201 the identity line renders the
bound-state indicator (plane + endpoint, never the key); bind failures surface
the error_code + bifrost_error in the setup error line.

Closes the persistent-memory caveat: web chat can now bind its own Tier-3
provider (memory persistence + affect telemetry), not persona+debug only.

Web suites 63 green (presentation-contract included); pure static HTML/JS.

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "ratatoskr"
-version = "0.17.12"
+version = "0.17.13"
 description = "Worldtree Conversation API debug TUI — multi-pane observability dashboard"
 readme = "README.md"
 requires-python = ">=3.12"

src/ratatoskr/web/static/index.html

@@ -510,6 +510,14 @@ body {
     <div class="select-wrap">
       <select id="agent-picker"><option>loading…</option></select>
     </div>
+    <label class="field-label" for="bifrost-plane">Bifrost binding (Tier-3 provider)</label>
+    <div class="select-wrap">
+      <select id="bifrost-plane">
+        <option value="">none — observe only</option>
+        <option value="memory">memory (:8391) — durable recall</option>
+        <option value="affect">affect (:8390) — persona / PAD</option>
+      </select>
+    </div>
     <button id="start-btn">open session</button>
     <div class="setup-err" id="setup-err"></div>
   </div>
@@ -734,19 +742,35 @@ async function startSession() {
   try {
     // end_user_id is server-configured (RATATOSKR_END_USER_ID) — not sent
     // from the browser; the server ignores any end_user_id in this body.
+    // Issue #17: the browser selects only the PLANE; the consumer key + host
+    // are server-held (the key never reaches the browser).
+    const plane = $("bifrost-plane").value;
+    const reqBody = { agent_id: agentId };
+    if (plane) reqBody.bifrost_plane = plane;
     const r = await fetch("/api/sessions", {
       method: "POST", headers: { "Content-Type": "application/json" },
-      body: JSON.stringify({ agent_id: agentId }),
+      body: JSON.stringify(reqBody),
     });
     if (r.status !== 201) {
-      $("setup-err").textContent = "create session failed: HTTP " + r.status;
+      let detail = "HTTP " + r.status;
+      try {
+        const err = await r.json();
+        if (err && err.error_code) {
+          detail = err.error_code + (err.bifrost_error ? " (" + err.bifrost_error + ")" : "");
+        }
+      } catch (_) { /* non-JSON body */ }
+      $("setup-err").textContent = "create session failed: " + detail;
       $("start-btn").disabled = false;
       return;
     }
     const info = await r.json();
     state.sessionId = info.session_id;
+    // Issue #17 bound-state indicator: plane + endpoint (never the key).
+    const boundTag = info.bifrost
+      ? ` · <span class="a">⇄ ${esc(info.bifrost.plane)}</span> ${esc(info.bifrost.endpoint)}`
+      : "";
     $("identity").innerHTML =
-      `<span class="a">${esc(agentId)}</span> · …${esc(info.session_id.slice(-8))}`;
+      `<span class="a">${esc(agentId)}</span> · …${esc(info.session_id.slice(-8))}${boundTag}`;
     setConn("idle", "connected");
     $("setup").style.display = "none";
     $("workspace").classList.add("live");

uv.lock

@@ -1052,7 +1052,7 @@ wheels = [
 
 [[package]]
 name = "ratatoskr"
-version = "0.17.12"
+version = "0.17.13"
 source = { editable = "." }
 dependencies = [
     { name = "httpx" },