Add nav-item + link-card fragments and oEmbed endpoint

- nav-item fragment handler with template
- link-card fragment handler with CID-based lookup, friendly names, batch mode
- oEmbed router at GET /oembed for media/recipe/effect/run content
- Fragment templates in app/templates/fragments/

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/__init__.py

@@ -164,13 +164,14 @@ def create_app() -> FastAPI:
         return JSONResponse({"detail": "Not found"}, status_code=404)
 
     # Include routers
-    from .routers import auth, storage, api, recipes, cache, runs, home, effects, inbox, fragments
+    from .routers import auth, storage, api, recipes, cache, runs, home, effects, inbox, fragments, oembed
 
     # Home and auth routers (root level)
     app.include_router(home.router, tags=["home"])
     app.include_router(auth.router, prefix="/auth", tags=["auth"])
     app.include_router(inbox.router, tags=["inbox"])
     app.include_router(fragments.router, tags=["fragments"])
+    app.include_router(oembed.router, tags=["oembed"])
 
     # Feature routers
     app.include_router(storage.router, prefix="/storage", tags=["storage"])

app/routers/fragments.py

@@ -5,6 +5,8 @@ Exposes HTML fragments at ``/internal/fragments/{type}`` for consumption
 by coop apps via the fragment client.
 """
 
+import os
+
 from fastapi import APIRouter, Request, Response
 
 router = APIRouter()
@@ -25,3 +27,117 @@ async def get_fragment(fragment_type: str, request: Request):
         return Response(content="", media_type="text/html", status_code=200)
     html = await handler(request)
     return Response(content=html, media_type="text/html", status_code=200)
+
+
+# --- nav-item fragment ---
+
+async def _nav_item_handler(request: Request) -> str:
+    from artdag_common import render_fragment
+
+    templates = request.app.state.templates
+    artdag_url = os.getenv("APP_URL_ARTDAG", "https://celery-artdag.rose-ash.com")
+    return render_fragment(templates, "fragments/nav_item.html", artdag_url=artdag_url)
+
+
+_handlers["nav-item"] = _nav_item_handler
+
+
+# --- link-card fragment ---
+
+async def _link_card_handler(request: Request) -> str:
+    from artdag_common import render_fragment
+    import database
+
+    templates = request.app.state.templates
+    cid = request.query_params.get("cid", "")
+    content_type = request.query_params.get("type", "media")
+    slug = request.query_params.get("slug", "")
+    keys_raw = request.query_params.get("keys", "")
+
+    # Batch mode: return multiple cards separated by markers
+    if keys_raw:
+        keys = [k.strip() for k in keys_raw.split(",") if k.strip()]
+        parts = []
+        for key in keys:
+            parts.append(f"<!-- fragment:{key} -->")
+            card_html = await _render_single_link_card(
+                templates, key, content_type,
+            )
+            parts.append(card_html)
+        return "\n".join(parts)
+
+    # Single mode: use cid or slug
+    lookup_cid = cid or slug
+    if not lookup_cid:
+        return ""
+    return await _render_single_link_card(templates, lookup_cid, content_type)
+
+
+async def _render_single_link_card(templates, cid: str, content_type: str) -> str:
+    import database
+    from artdag_common import render_fragment
+
+    if not cid:
+        return ""
+
+    artdag_url = os.getenv("APP_URL_ARTDAG", "https://celery-artdag.rose-ash.com")
+
+    # Try item_types first (has metadata)
+    item = await database.get_item_types(cid)
+    # get_item_types returns a list; pick best match for content_type
+    meta = None
+    if item:
+        for it in item:
+            if it.get("type") == content_type:
+                meta = it
+                break
+        if not meta:
+            meta = item[0]
+
+    # Try friendly name for display
+    friendly = None
+    if meta and meta.get("actor_id"):
+        friendly = await database.get_friendly_name_by_cid(meta["actor_id"], cid)
+
+    # Try run cache if type is "run"
+    run = None
+    if content_type == "run":
+        run = await database.get_run_cache(cid)
+
+    title = ""
+    description = ""
+    link = ""
+
+    if friendly:
+        title = friendly.get("display_name") or friendly.get("base_name", cid[:12])
+    elif meta:
+        title = meta.get("filename") or meta.get("description", cid[:12])
+    elif run:
+        title = f"Run {cid[:12]}"
+    else:
+        title = cid[:16]
+
+    if meta:
+        description = meta.get("description", "")
+
+    if content_type == "run":
+        link = f"{artdag_url}/runs/{cid}"
+    elif content_type == "recipe":
+        link = f"{artdag_url}/recipes/{cid}"
+    elif content_type == "effect":
+        link = f"{artdag_url}/effects/{cid}"
+    else:
+        link = f"{artdag_url}/cache/{cid}"
+
+    return render_fragment(
+        templates, "fragments/link_card.html",
+        title=title,
+        description=description,
+        link=link,
+        cid=cid,
+        content_type=content_type,
+        artdag_url=artdag_url,
+    )
+
+
+_handlers["link-card"] = _link_card_handler

app/routers/oembed.py

@@ -0,0 +1,74 @@
+"""Art-DAG oEmbed endpoint.
+
+Returns oEmbed JSON responses for Art-DAG content (media, recipes, effects, runs).
+"""
+
+import os
+
+from fastapi import APIRouter, Request
+from fastapi.responses import JSONResponse
+
+router = APIRouter()
+
+
+@router.get("/oembed")
+async def oembed(request: Request):
+    url = request.query_params.get("url", "")
+    if not url:
+        return JSONResponse({"error": "url parameter required"}, status_code=400)
+
+    # Parse URL to extract content type and CID
+    # URL patterns: /cache/{cid}, /recipes/{cid}, /effects/{cid}, /runs/{cid}
+    from urllib.parse import urlparse
+
+    parsed = urlparse(url)
+    parts = [p for p in parsed.path.strip("/").split("/") if p]
+
+    if len(parts) < 2:
+        return JSONResponse({"error": "could not parse content URL"}, status_code=404)
+
+    content_type = parts[0].rstrip("s")  # recipes -> recipe, runs -> run
+    cid = parts[1]
+
+    import database
+
+    title = cid[:16]
+    thumbnail_url = None
+
+    # Look up metadata
+    items = await database.get_item_types(cid)
+    if items:
+        meta = items[0]
+        title = meta.get("filename") or meta.get("description") or title
+
+        # Try friendly name
+        actor_id = meta.get("actor_id")
+        if actor_id:
+            friendly = await database.get_friendly_name_by_cid(actor_id, cid)
+            if friendly:
+                title = friendly.get("display_name") or friendly.get("base_name", title)
+
+        # Media items get a thumbnail
+        if meta.get("type") == "media":
+            artdag_url = os.getenv("APP_URL_ARTDAG", "https://celery-artdag.rose-ash.com")
+            thumbnail_url = f"{artdag_url}/cache/{cid}/raw"
+
+    elif content_type == "run":
+        run = await database.get_run_cache(cid)
+        if run:
+            title = f"Run {cid[:12]}"
+
+    artdag_url = os.getenv("APP_URL_ARTDAG", "https://celery-artdag.rose-ash.com")
+
+    resp = {
+        "version": "1.0",
+        "type": "link",
+        "title": title,
+        "provider_name": "art-dag",
+        "provider_url": artdag_url,
+        "url": url,
+    }
+    if thumbnail_url:
+        resp["thumbnail_url"] = thumbnail_url
+
+    return JSONResponse(resp)

app/templates/fragments/link_card.html

@@ -0,0 +1,22 @@
+<a href="{{ link }}" class="block rounded border border-stone-200 bg-white hover:bg-stone-50 transition-colors no-underline" data-fragment="link-card" data-app="artdag" data-hx-disable>
+  <div class="flex flex-row items-center gap-3 p-3">
+    <div class="flex-shrink-0 w-10 h-10 rounded bg-stone-100 flex items-center justify-center text-stone-500">
+      {% if content_type == "recipe" %}
+        <i class="fas fa-scroll text-sm"></i>
+      {% elif content_type == "effect" %}
+        <i class="fas fa-magic text-sm"></i>
+      {% elif content_type == "run" %}
+        <i class="fas fa-play-circle text-sm"></i>
+      {% else %}
+        <i class="fas fa-cube text-sm"></i>
+      {% endif %}
+    </div>
+    <div class="flex-1 min-w-0">
+      <div class="font-medium text-stone-900 text-sm truncate">{{ title }}</div>
+      {% if description %}
+        <div class="text-xs text-stone-500 clamp-2">{{ description }}</div>
+      {% endif %}
+      <div class="text-xs text-stone-400 mt-0.5">{{ content_type }} &middot; {{ cid[:12] }}&hellip;</div>
+    </div>
+  </div>
+</a>

app/templates/fragments/nav_item.html

@@ -0,0 +1,7 @@
+<div class="relative nav-group">
+  <a href="{{ artdag_url }}"
+     class="justify-center cursor-pointer flex flex-row items-center gap-2 rounded bg-stone-200 text-black p-3"
+     data-hx-disable>
+    <i class="fas fa-project-diagram text-sm"></i> art-dag
+  </a>
+</div>