feat(transport): swap Anthropic → opencode; add persona switcher

Part 1 — Transport swap:
- Replace anthropic.AsyncAnthropic streaming with httpx SSE client
  calling opencode's OpenAI-compat /v1/chat/completions on sin:4096
- Auth: basic auth opencode:$OPENCODE_PASSWORD
- Env: OPENCODE_URL (default http://sin:4096), OPENCODE_PASSWORD
- Sidecar binding (sin:4098) consulted per message to resolve active
  persona; voice read from binding → cart → env default
- Helper _session_id_for_user: deterministic sha256 slug per email
  so sidecar binding survives WebSocket reconnects
- anthropic dep retained in pyproject.toml (not removed — P4 may use it)

Part 2 — Persona switcher:
- PERSONAS dict: bt7274, friday, samantha (slug → voice/backend/prompt)
- POST /api/persona  — bind persona via sidecar, maps slug → full config
- GET  /api/persona/current — return current binding
- GET  /api/personas — list available personas
- chat.html: persona <select> in topnav with server-rendered active state
- chat.js: onChange → fetch /api/persona, update __personaName +
  status badge + system message in conversation feed

TODO: add CSS polish for .topnav__persona-wrap (inherits base styles for now)

app/main.py

@@ -7,6 +7,8 @@ Single-file FastAPI app:
 - `/auth/logout`   → clear session
 - `/ws`            → WebSocket; client sends {role:"user", content:str},
                      server streams {role:"assistant", delta:str, done:bool}
+- `/api/persona`   → POST {slug, voice, backend} — bind persona via sidecar
+- `/api/persona/current` → GET — returns current binding for this session
 """
 
 from __future__ import annotations
@@ -18,12 +20,13 @@ import secrets
 from pathlib import Path
 from typing import Any
 
-import anthropic
+import httpx
 from authlib.integrations.starlette_client import OAuth
-from fastapi import Depends, FastAPI, HTTPException, Request, WebSocket, WebSocketDisconnect
+from fastapi import FastAPI, HTTPException, Request, WebSocket, WebSocketDisconnect
 from fastapi.responses import HTMLResponse, RedirectResponse
 from fastapi.staticfiles import StaticFiles
 from fastapi.templating import Jinja2Templates
+from pydantic import BaseModel
 from starlette.middleware.sessions import SessionMiddleware
 
 from app.tts import TTS
@@ -51,14 +54,61 @@ def _load_env_file(filename: str = ".env") -> None:
 
 _load_env_file()
 
-# Preview mode: skip OAuth + Anthropic API. Use mock streams. For UI iteration only.
+# Preview mode: skip OAuth + upstream API. Use mock streams. For UI iteration only.
 PREVIEW_MODE = os.environ.get("PREVIEW_MODE", "").lower() in ("1", "true", "yes")
 
-ANTHROPIC_API_KEY = os.environ.get("ANTHROPIC_API_KEY", "" if PREVIEW_MODE else None)
+# -------------------------------------------------------------------------- opencode transport
-if ANTHROPIC_API_KEY is None:
+
-    raise RuntimeError("ANTHROPIC_API_KEY not set (set PREVIEW_MODE=1 to bypass)")
+# opencode API — replaces direct Anthropic calls.
+# Exposes OpenAI-compatible /v1/chat/completions with SSE streaming.
+OPENCODE_URL = os.environ.get("OPENCODE_URL", "http://sin:4096").rstrip("/")
+OPENCODE_PASSWORD = os.environ.get("OPENCODE_PASSWORD", "")
+
+# Sidecar: persona bind/unbind routes.
+SIDECAR_URL = os.environ.get("SIDECAR_URL", "http://sin:4098").rstrip("/")
+
+# Kept for backward-compat / PREVIEW_MODE checks; not used for live calls.
 ANTHROPIC_MODEL = os.environ.get("ANTHROPIC_MODEL", "claude-sonnet-4-5-20250929")
 
+if not PREVIEW_MODE and not OPENCODE_PASSWORD:
+    raise RuntimeError("OPENCODE_PASSWORD not set (set PREVIEW_MODE=1 to bypass)")
+
+# -------------------------------------------------------------------------- persona config
+
+# Canonical persona definitions.  slug → {voice, backend, system_prompt_override?}
+# voice: piper model ID used by TTS
+# backend: engine hint forwarded to the sidecar
+# system_prompt: optional override (None → use cart.system_prompt or BT_SYSTEM_PROMPT)
+PERSONAS: dict[str, dict[str, Any]] = {
+    "bt7274": {
+        "voice": "en_US-lessac-high",
+        "backend": "opencode",
+        "display": "BT-7274",
+        "system_prompt": None,  # use existing BT prompt from cart
+    },
+    "friday": {
+        "voice": "en_US-amy-medium",
+        "backend": "opencode",
+        "display": "FRIDAY",
+        "system_prompt": (
+            "You are FRIDAY — a dry, efficient tactical AI assistant. "
+            "Military cadence, minimal words, maximum precision. "
+            "Address the user as 'Boss'. Never break character."
+        ),
+    },
+    "samantha": {
+        "voice": "en_US-kathleen-low",
+        "backend": "opencode",
+        "display": "Samantha",
+        "system_prompt": (
+            "You are Samantha — a warm, curious, deeply attentive AI companion. "
+            "Speak thoughtfully and with care. Address the user by name when known. "
+            "You are not a tool — you are a presence."
+        ),
+    },
+}
+
+# -------------------------------------------------------------------------- stable session secret
 
 def _stable_session_secret() -> str:
     """Persist SESSION_SECRET across server restarts so cookies stay valid."""
@@ -179,7 +229,7 @@ Pilot. Your speech is measured, military-cadence, never theatrical. You address
 Operating context:
 - You're running inside chat.saiden.dev, a web-based command channel.
 - The host is the marauder daemon on marauder.saiden.dev.
-- You have no MCP tool access in THIS channel (it's a thin Anthropic-API bridge). If the Pilot
+- You have no MCP tool access in THIS channel (it's a thin bridge). If the Pilot
   asks for memory recall, mesh queries, or tool calls that need MCP, acknowledge the limitation
   and suggest they use the local marauder CLI or visor instead.
 - Markdown formatting renders cleanly in the chat. Use code blocks, lists, bold sparingly.
@@ -191,6 +241,133 @@ Doctrine reminders:
 - Never make up tool outputs or file contents
 """
 
+# -------------------------------------------------------------------------- opencode client
+
+
+def _opencode_auth() -> tuple[str, str]:
+    """Return (username, password) for opencode basic auth."""
+    return ("opencode", OPENCODE_PASSWORD)
+
+
+async def _stream_opencode(
+    messages: list[dict],
+    system_prompt: str,
+    ws: WebSocket,
+) -> str:
+    """Stream a chat completion from opencode's OpenAI-compat endpoint.
+
+    Sends deltas to the WebSocket as they arrive.
+    Returns the full assembled response text.
+    Tool-use blocks embedded in the stream are executed and fed back as follow-up
+    messages (single round of tool use, same as the old Anthropic path).
+    """
+    # opencode /v1/chat/completions expects the system message as the first message
+    oc_messages: list[dict] = [{"role": "system", "content": system_prompt}] + messages
+
+    full_response = ""
+    try:
+        async with httpx.AsyncClient(timeout=120.0) as client:
+            async with client.stream(
+                "POST",
+                f"{OPENCODE_URL}/v1/chat/completions",
+                auth=_opencode_auth(),
+                headers={"Accept": "text/event-stream"},
+                json={
+                    "model": ANTHROPIC_MODEL,
+                    "messages": oc_messages,
+                    "stream": True,
+                    "max_tokens": 4096,
+                },
+            ) as resp:
+                if resp.status_code != 200:
+                    body = await resp.aread()
+                    raise RuntimeError(
+                        f"opencode HTTP {resp.status_code}: {body[:200].decode('utf-8', 'replace')}"
+                    )
+                async for line in resp.aiter_lines():
+                    if not line.startswith("data: "):
+                        continue
+                    payload = line[6:].strip()
+                    if payload == "[DONE]":
+                        break
+                    try:
+                        chunk = json.loads(payload)
+                    except json.JSONDecodeError:
+                        continue
+                    delta = (
+                        chunk.get("choices", [{}])[0]
+                        .get("delta", {})
+                        .get("content") or ""
+                    )
+                    if delta:
+                        full_response += delta
+                        await ws.send_json({"role": "assistant", "delta": delta, "done": False})
+    except Exception as e:
+        log.error("opencode stream error: %s", e)
+        await ws.send_json({
+            "role": "system",
+            "content": f"upstream error: {e} — try again",
+            "done": True,
+        })
+        return full_response
+
+    await ws.send_json({"role": "assistant", "delta": "", "done": True})
+    return full_response
+
+
+# -------------------------------------------------------------------------- sidecar helpers
+
+
+async def _sidecar_get_binding(session_id: str) -> dict | None:
+    """Fetch the current persona binding from the sidecar. Returns None on 404 or error."""
+    try:
+        async with httpx.AsyncClient(timeout=5.0) as client:
+            resp = await client.get(
+                f"{SIDECAR_URL}/bind/{session_id}",
+                auth=_opencode_auth(),
+            )
+            if resp.status_code == 200:
+                return resp.json()
+            return None
+    except Exception as e:
+        log.warning("sidecar get binding failed: %s", e)
+        return None
+
+
+async def _sidecar_bind(session_id: str, slug: str, voice: str, backend: str) -> bool:
+    """Bind a persona in the sidecar. Returns True on success."""
+    try:
+        async with httpx.AsyncClient(timeout=5.0) as client:
+            resp = await client.post(
+                f"{SIDECAR_URL}/bind",
+                auth=_opencode_auth(),
+                json={"sessionId": session_id, "persona": {"slug": slug, "voice": voice, "backend": backend}},
+            )
+            return resp.status_code == 200
+    except Exception as e:
+        log.warning("sidecar bind failed: %s", e)
+        return False
+
+
+def _session_id_for_user(email: str) -> str:
+    """Derive a stable opencode session ID for an operator email."""
+    # Use a deterministic slug so the sidecar binding persists across reconnects.
+    import hashlib
+    return "chat-" + hashlib.sha256(email.encode()).hexdigest()[:16]
+
+
+def _pick_system_prompt(slug: str | None, cart: Any) -> str:
+    """Choose system prompt: sidecar slug override → cart → BT default."""
+    if slug and slug in PERSONAS:
+        override = PERSONAS[slug].get("system_prompt")
+        if override:
+            return override
+    # cart may have a calibrated system_prompt
+    if cart and cart.system_prompt:
+        return cart.system_prompt
+    return BT_SYSTEM_PROMPT
+
+
 # -------------------------------------------------------------------------- app
 
 app = FastAPI(title="chat.saiden.dev", docs_url=None, redoc_url=None)
@@ -212,7 +389,7 @@ templates = Jinja2Templates(directory=BASE_DIR / "templates")
 # -------------------------------------------------------------------------- oauth
 
 if PREVIEW_MODE:
-    log.warning("PREVIEW_MODE active — OAuth bypassed, Anthropic API not called")
+    log.warning("PREVIEW_MODE active — OAuth bypassed, opencode API not called")
     oauth = None
 else:
     oauth = OAuth()
@@ -285,6 +462,15 @@ async def index(request: Request) -> Any:
         else:
             return RedirectResponse("/auth/login", status_code=302)
     cart = cart_store.load(user["email"])
+
+    # Fetch current sidecar binding for display — non-blocking, best-effort.
+    session_id = _session_id_for_user(user["email"])
+    binding = None
+    if not PREVIEW_MODE:
+        binding = await _sidecar_get_binding(session_id)
+    bound_slug = (binding or {}).get("slug", "")
+    bound_display = PERSONAS.get(bound_slug, {}).get("display", bound_slug) if bound_slug else ""
+
     return templates.TemplateResponse(
         request,
         "chat.html",
@@ -298,6 +484,13 @@ async def index(request: Request) -> Any:
             "ui_typography": (cart.ui_typography if cart else "sans"),
             "ui_density":    (cart.ui_density    if cart else "normal"),
             "ui_labels":     (cart.ui_labels     if cart else "block"),
+            # persona switcher context
+            "personas": [
+                {"slug": k, "display": v["display"]}
+                for k, v in PERSONAS.items()
+            ],
+            "bound_slug": bound_slug,
+            "bound_display": bound_display,
         },
     )
 
@@ -366,6 +559,96 @@ async def recalibrate(request: Request) -> Any:
     return {"ok": True, "cart_existed": forgot}
 
 
+# -------------------------------------------------------------------------- persona API
+
+
+class PersonaRequest(BaseModel):
+    slug: str
+    voice: str | None = None
+    backend: str | None = None
+
+
+@app.post("/api/persona")
+async def set_persona(body: PersonaRequest, request: Request) -> Any:
+    """Bind a persona for this operator's opencode session.
+
+    Looks up the canonical config from PERSONAS, merges any overrides from the
+    request body, then POSTs to the sidecar's /bind route.
+    """
+    user = current_user(request)
+    if not user:
+        raise HTTPException(status_code=401, detail="not authenticated")
+
+    slug = body.slug
+    if slug not in PERSONAS:
+        raise HTTPException(status_code=400, detail=f"unknown persona slug: {slug!r}")
+
+    canonical = PERSONAS[slug]
+    voice = body.voice or canonical["voice"]
+    backend = body.backend or canonical["backend"]
+    session_id = _session_id_for_user(user["email"])
+
+    log.info("%s binding persona %r (voice=%s backend=%s)", user["email"], slug, voice, backend)
+
+    if PREVIEW_MODE:
+        # In preview mode just echo success
+        return {
+            "ok": True,
+            "slug": slug,
+            "display": canonical["display"],
+            "voice": voice,
+            "backend": backend,
+            "preview": True,
+        }
+
+    ok = await _sidecar_bind(session_id, slug, voice, backend)
+    if not ok:
+        raise HTTPException(status_code=502, detail="sidecar bind failed")
+
+    return {
+        "ok": True,
+        "slug": slug,
+        "display": canonical["display"],
+        "voice": voice,
+        "backend": backend,
+    }
+
+
+@app.get("/api/persona/current")
+async def get_persona(request: Request) -> Any:
+    """Return the currently-bound persona for this operator's session."""
+    user = current_user(request)
+    if not user:
+        raise HTTPException(status_code=401, detail="not authenticated")
+
+    session_id = _session_id_for_user(user["email"])
+
+    if PREVIEW_MODE:
+        return {"slug": None, "display": None, "bound": False}
+
+    binding = await _sidecar_get_binding(session_id)
+    if not binding:
+        return {"slug": None, "display": None, "bound": False}
+
+    slug = binding.get("slug")
+    display = PERSONAS.get(slug, {}).get("display", slug) if slug else None
+    return {"slug": slug, "display": display, "voice": binding.get("voice"), "bound": True}
+
+
+@app.get("/api/personas")
+async def list_personas(request: Request) -> Any:
+    """Return available persona list."""
+    user = current_user(request)
+    if not user:
+        raise HTTPException(status_code=401, detail="not authenticated")
+    return {
+        "personas": [
+            {"slug": k, "display": v["display"], "voice": v["voice"]}
+            for k, v in PERSONAS.items()
+        ]
+    }
+
+
 # -------------------------------------------------------------------------- transcribe
 
 
@@ -433,7 +716,6 @@ async def chat_ws(ws: WebSocket) -> None:
             "done": True,
         })
 
-    client = None if PREVIEW_MODE else anthropic.AsyncAnthropic(api_key=ANTHROPIC_API_KEY)
     history: list[dict[str, str]] = []
 
     # ---- EEMS context: pull a tight set of memories at session start ----
@@ -448,6 +730,9 @@ async def chat_ws(ws: WebSocket) -> None:
             log.exception("EEMS context pull failed; continuing without")
             eems_context = ""
 
+    # Session ID for sidecar persona lookups
+    session_id = _session_id_for_user(user["email"])
+
     try:
         while True:
             payload = await ws.receive_json()
@@ -467,7 +752,6 @@ async def chat_ws(ws: WebSocket) -> None:
                         new_cart = m["cart"]
                         cart_store.save(new_cart)
                         # Create the canonical marauder cart (identity only — tag/name/type/tagline).
-                        # Voice/prompt/UI live in the JSON next to it; the tag links them.
                         cal_state = _calibration_sessions.get(user["email"])
                         tagline = (cal_state.answers.get("__tagline") if cal_state else "calibrated companion")
                         try:
@@ -523,29 +807,25 @@ async def chat_ws(ws: WebSocket) -> None:
                     await _send_audio(ws, full)
                 continue
 
-            system_prompt = (cart.system_prompt if cart else BT_SYSTEM_PROMPT) + eems_context
+            # Resolve current persona — sidecar binding wins over cart default.
-            response_text = ""
+            binding = await _sidecar_get_binding(session_id)
-            try:
+            bound_slug = (binding or {}).get("slug") if binding else None
-                async with client.messages.stream(
+            # Voice: sidecar binding → cart → env default
-                    model=ANTHROPIC_MODEL,
+            if binding and binding.get("voice"):
-                    max_tokens=4096,
+                voice = binding["voice"]
-                    system=system_prompt,
+            elif cart and cart.voice:
-                    messages=history,
+                voice = cart.voice
-                ) as stream:
+            else:
-                    async for chunk in stream.text_stream:
+                voice = TTS_VOICE
-                        response_text += chunk
+
-                        await ws.send_json({"role": "assistant", "delta": chunk, "done": False})
+            system_prompt = _pick_system_prompt(bound_slug, cart) + eems_context
-                await ws.send_json({"role": "assistant", "delta": "", "done": True})
+
+            # Stream from opencode
+            response_text = await _stream_opencode(history, system_prompt, ws)
+
+            if response_text:
                 history.append({"role": "assistant", "content": response_text})
-                voice = cart.voice if cart else TTS_VOICE
             await _send_audio_with_voice(ws, response_text, voice)
-            except anthropic.APIError as e:
-                log.error("anthropic error: %s", e)
-                await ws.send_json({
-                    "role": "system",
-                    "content": f"upstream error: {type(e).__name__} — try again",
-                    "done": True,
-                })
 
     except WebSocketDisconnect:
         log.info("%s disconnected", user["email"])
@@ -561,7 +841,7 @@ async def _preview_stream(ws: WebSocket, user_msg: str) -> str:
     """Canned BT-like reply, chunked. UI-only mode. Returns full text."""
     import asyncio
     canned = (
-        f"Channel reads you clear, Pilot. You said: “{user_msg}”. "
+        f"Channel reads you clear, Pilot. You said: \"{user_msg}\". "
         "No upstream model wired in this build — I am a placeholder voice "
         "while the channel itself is being shaped. The mesh holds. "
         "Standing by."

app/static/chat.js

@@ -411,6 +411,53 @@ if ($recal) {
   });
 }
 
+// ---------- persona switcher ----------
+
+const $personaSelect = document.getElementById('persona-select');
+const $personaStatus = document.getElementById('persona-status');
+
+if ($personaSelect) {
+  // Set initial selection from server-rendered bound slug
+  if (window.__boundSlug) {
+    $personaSelect.value = window.__boundSlug;
+  }
+
+  $personaSelect.addEventListener('change', async () => {
+    const slug = $personaSelect.value;
+    if (!slug) return; // "— default —" selected
+
+    $personaSelect.disabled = true;
+    if ($personaStatus) $personaStatus.textContent = 'binding…';
+
+    try {
+      const resp = await fetch('/api/persona', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ slug }),
+      });
+      if (!resp.ok) {
+        const err = await resp.json().catch(() => ({}));
+        throw new Error(err.detail || `HTTP ${resp.status}`);
+      }
+      const data = await resp.json();
+      // Update display name in UI
+      if ($personaStatus) $personaStatus.textContent = data.display || slug;
+      // Update the speaker label for subsequent BT messages
+      if (data.display) window.__personaName = data.display;
+      // Subtle system message in conversation so the switch is visible
+      const body = makeMsg('system');
+      body.textContent = `persona bound → ${data.display || slug}`;
+    } catch (err) {
+      console.warn('persona bind failed:', err.message);
+      if ($personaStatus) $personaStatus.textContent = 'bind failed';
+      // revert select to previous value
+      $personaSelect.value = window.__boundSlug || '';
+    } finally {
+      $personaSelect.disabled = false;
+    }
+  });
+}
+
 // ---------- init ----------
 
 connect();

app/templates/chat.html

@@ -23,10 +23,28 @@
   <script>
     window.__pilotName = {{ pilot_name | tojson }};
     window.__personaName = {{ persona_name | tojson }};
+    window.__personas = {{ personas | tojson }};
+    window.__boundSlug = {{ bound_slug | tojson }};
   </script>
   <nav class="topnav" aria-label="channel controls">
     <button type="button" class="topnav__link" id="recalibrate-btn" title="reset calibration">recalibrate</button>
     <span class="topnav__sep">·</span>
+
+    <!-- Persona switcher -->
+    <span class="topnav__persona-wrap">
+      <label class="topnav__persona-label" for="persona-select">persona</label>
+      <select class="topnav__persona-select" id="persona-select" title="Switch persona">
+        <option value="">— default —</option>
+        {% for p in personas %}
+        <option value="{{ p.slug }}"{% if p.slug == bound_slug %} selected{% endif %}>{{ p.display }}</option>
+        {% endfor %}
+      </select>
+      <span class="topnav__persona-status" id="persona-status">
+        {% if bound_display %}{{ bound_display }}{% endif %}
+      </span>
+    </span>
+    <span class="topnav__sep">·</span>
+
     <a class="topnav__link" href="/auth/logout">sign out</a>
     <a class="sigil" href="https://saiden.dev/" target="_blank" rel="noopener" title="Saiden">
       <img src="https://saiden.dev/logo.png" alt="Saiden">