docs(design): record video preparation integration

.project-docs/10-decisions/adr-007-ai-design-living-form-v2.md

@@ -2,16 +2,19 @@
 
 ## Status
 
-Accepted / implemented, amended 2026-09-07
+Accepted / implemented, amended 2026-09-16
 
 Amended on 2026-09-07 to define operation-scoped public activity as transient
 presentation state beneath the matching optimistic user message.
 
+Amended on 2026-09-16 to prepare a coherent video draft before quotation and expose
+an explicit starting-image binding with capability-driven controls.
+
 ## Date
 
 2026-08-30
 
-Last amended: 2026-09-07
+Last amended: 2026-09-16
 
 ## Context
 
@@ -48,6 +51,15 @@ are expressed through public Prompt aliases bound to canonical Assets.
   plan, warnings, expiry, and Token Point amount and confirms only the Quote ID.
   Provider prompts, models, routing, storage, safety evidence, and billing atoms stay
   server-private.
+- Before requesting a Quote, the client applies `prepare_generation` through the
+  same Main-owned input contract and uses the returned current revision. Preparation
+  never fabricates a chat Turn or confirms paid generation. A definitive preparation
+  failure stops quotation even when a live blocker event was missed; transport-unknown
+  recovery keeps the original operation identity.
+- Media availability, ratios, duration and output limits come from the server's
+  per-medium `generation_options`, not invented client defaults. The selected
+  supported duration must be saved, not merely displayed. Semantic video motion is
+  arranged by the server Reasoner and the returned creator prompt becomes visible.
 - Electron Main is the only Canvas network authority. Development and packaged
   builds use the Works Square V2 contract; there is no V1 DTO adapter, local semantic
   adapter, mutable Quote PATCH, editable provider Prompt, or cloud-failure fallback.
@@ -59,8 +71,11 @@ are expressed through public Prompt aliases bound to canonical Assets.
 - The public `content.concept` projection is the directly editable final Prompt.
   References retain stable reference IDs and typed Workspace Asset bindings while
   appearing in that Prompt as continuous `@图片N` aliases. The Prompt is the only
-  visible expression of how a reference affects generation; the adjacent row manages
-  binding/file state only. An unbound referenced alias blocks Quote availability and
+  visible expression of creative reference intent; the adjacent row manages
+  binding/file state and explicitly selects the video starting image. That selection
+  binds both `first_frame` role and Asset identity, independently of an alias token.
+  Unsupported retained references remain visible until the user explicitly changes
+  or unbinds them; their Assets are never silently deleted. An unbound referenced alias blocks Quote availability and
   exposes a targeted upload slot.
 - Prompt, reference binding, type, aspect-ratio, duration, or output-count changes
   enter the existing typed reducer and create a new Specification revision. An offered
@@ -94,6 +109,10 @@ and uncertain retries auditable without exposing provider internals.
 
 ## Related
 
+- Video preparation source `1acca836fe035dd462110cdc7683645c1e031f54`, task
+  `20260916-design-media-client-a7d3e9c1`, integrated by
+  `20260916-merge-design-video-client-4f6d28a1` with matching server
+  `1a3df8df08033adb2bec8d268ca2c18e7b785e1e`.
 - Client source `b0b5a602b501308a23eb27e2f51a5169b9e46b1e`
 - Server source `b5351d54f595ce8eb873593e462e4a556bea0b05`
 - Server ADR `ADR-2026-08-28-001`