feat: add conversation image previews and sharing

docs/api.md

@@ -75,6 +75,8 @@ an administrator credential.
 | `POST` | `/api/conversations/{id}/suggest-reply` | Generate a reply suggestion | admin | yes |
 | `POST` | `/api/conversations/{id}/suggest-media-ask` | Generate a media request suggestion | admin | yes |
 | `POST` | `/api/conversations/{id}/send-reply` | Send a conversation reply | admin | yes |
+| `GET` | `/api/conversations/{id}/shareable-media` | List exchange-library images allowed for the latest inbound request | read | no |
+| `POST` | `/api/conversations/{id}/share-media` | Send a selected exchange-library image | admin | yes |
 | `POST` | `/api/conversations/start` | Start a new conversation | admin | yes |
 | `GET` | `/api/media` | List received private media | read | no |
 | `GET` | `/api/media/sync` | Get media sync state | read | no |

docs/data-flow.md

@@ -104,6 +104,8 @@ For each latest inbound text event, `MediaLibraryExchangeService` detects direct
 
 After the normal reply limiter waits, automation refreshes Matrix and rechecks that the same inbound request is still latest and that no image, boundary, seller signal, or other terminal state has appeared. It then uploads the private file to Matrix, sends an `m.image` event with a stable transaction ID, and only after confirmation sends the optional reciprocal text. If the image is confirmed but the text is not, the asset remains consumed and the conversation is handed to the operator rather than risking a duplicate.
 
+The conversation UI also supports an explicitly confirmed manual choice from this same eligible set. Its read endpoint reports request-matched options without exposing filesystem paths. The send endpoint refreshes the conversation inside the owning account's rate limiter, rechecks the latest inbound request and safety boundaries, reserves the selected asset in the same durable ledger, and uses the same Matrix image-plus-reciprocal delivery path. A successful manual share marks automation as user-overridden.
+
 Conversation performance is derived from the complete attributed inbound transcript. Engagement cannot become a prompt-learning example while automation is active, and a later decline, boundary, or upsell removes an earlier example before future prompts load it.
 
 ## Dashboard data and events

docs/frontend.md

@@ -57,10 +57,12 @@ Rules:
 
 The login form exchanges the administrator token for an HttpOnly, SameSite=Strict cookie. API clients may use Bearer tokens. Express applies auth before static dashboard assets, APIs, SSE, and `/media`; `/healthz` is the intentional public exception.
 
-Media may be private conversation content. Preserve authenticated URLs, blur/privacy defaults, explicit reveal behavior, safe new-tab links, and no token leakage into query strings or local storage.
+Media may be private conversation content. Preserve authenticated URLs, blur/privacy defaults, explicit reveal behavior, safe new-tab links, and no token leakage into query strings or local storage. A conversation's source-post thumbnail becomes a keyboard-accessible full-screen preview only after the operator reveals it; the preview closes by button, backdrop, or Escape and restores focus to its trigger.
 
 Exchange-library uploads require an explicit consent checkbox before the raw image request is enabled. Previews remain blurred by default. The management card exposes AI tags, safety level, confidence/review state, enablement, and a two-step delete action. Its progression rail mirrors the actual nonspecific-request selection tiers rather than implying that explicit anatomy requests follow the same sequence.
 
+Conversation reply composers include a collapsed saved-image picker. It lists only server-approved assets for the latest inbound request, keeps thumbnails blurred until revealed, and requires selection plus a dedicated confirmation dialog before sending. The server remains authoritative and may reject a choice if the conversation changes before the rate-limited send executes.
+
 ## Feature structure
 
 Each route is a slice under `features/<name>/` with page/route components, local styles, and feature-specific helpers. Cross-feature visual/domain components live under `components/`; application lifecycle belongs under `app/`; transport belongs under `api/`.

docs/product-and-safety.md

@@ -57,6 +57,8 @@ Nonspecific requests broaden progressively within one conversation. The first se
 
 Reddit candidate eligibility remains the product's adult-entry assumption; this feature adds no separate verification workflow. Existing deterministic underage disclosures and conversation boundaries still stop automation before a library send.
 
+The conversation dashboard may let an operator choose the specific library asset, but it does not waive these rules. The picker exposes only enabled, unused assets that match the latest inbound request and its current safety tier. A manual choice is revalidated after rate-limit waiting, requires explicit send confirmation, and moves the conversation to operator-owned state after a confirmed delivery.
+
 ## Success and analytics
 
 Do not collapse all progress into “messages sent.” Useful states include: