اضافه شدن قابلیت share و نگهداری بلندمدت

docs/API.md

@@ -7,9 +7,9 @@ Cross-origin browser access is allowed only from `https://git.sadentel.net`, wit
 Optional fields:
 
 - `access`: `private` (default) or `unlisted`.
-- `expires_in`: positive integer seconds, maximum `LINK_TTL_SECONDS`. Expiry starts at upload acceptance, including queue time.
+- `expires_in`: `-1` for unlimited retention, or positive integer seconds up to `LINK_TTL_SECONDS`. Omit to use the configured finite default. `0` and values below `-1` are invalid. Finite expiry starts at upload acceptance, including queue time.
 
-HTTP 202 includes `id`, `status`, `viewer_url`, `status_url`, `expires_at` (Unix seconds), `access`, and a `viewer_token` for private uploads. `Location` points to status and `Retry-After: 1` provides a polling interval. Do not automatically retry a POST after a transport failure: each accepted request creates a new resource. Idempotency keys are not implemented.
+HTTP 202 includes `id`, `status`, `viewer_url`, `status_url`, `expires_at` (Unix seconds, or `-1` for no expiry), `access`, and a `viewer_token` for private uploads. `Location` points to status and `Retry-After: 1` provides a polling interval. Do not automatically retry a POST after a transport failure: each accepted request creates a new resource. Idempotency keys are not implemented.
 
 `GET .../{id}/status` returns HTTP 200 for existing, accessible, unexpired jobs, including failed jobs with `success: false` and a stable `error.code`. Failed artifacts return HTTP 422. Status does not disclose the original filename, source bytes or read token. The returned base `viewer_url` omits the original token: retain the initial URL or append your retained read token as a fragment.
 
@@ -49,3 +49,21 @@ A worker crash is retried after its lease expires, at most twice total. A parse
 ## PCB preview and comparison
 
 `POST /api/v1/pcbs/render` accepts `file`; `POST /api/v1/pcbs/comparisons` accepts `old_file` and `new_file`. Both require native `.PcbDoc` and reuse the existing asynchronous status, authentication, access and expiry conventions. They do not change schematic routes. See [PCB API and read/viewer endpoints](PCB.md).
+
+## Unlimited links and embedding
+
+All four creation operations (and the schematic comparison alias) accept `expires_in=-1`. The initial response and every status response return `expires_at: -1`. This sentinel is stored in the existing non-null timestamp column; no schema migration is required. Unlimited jobs remain claimable, count toward pending queue limits, retain private-token authorization, and are excluded from automatic expiry cleanup in both local and S3 storage. Other finite expiry behavior is unchanged. This is durable storage retention, not permanent RAM residency. External administrator deletion or provider lifecycle policies can still remove objects.
+
+The upload results and authenticated/accessible viewers provide a **Share** button. It reveals a copyable iframe snippet using the complete viewer URL, including the read-token fragment for a private design. Sharing that snippet shares read access; it does not make the job `unlisted`, expose the service API key or bypass CSP. The viewer recovers its token from the resource-specific browser session if the fragment was already removed. Embedding remains restricted to the service itself and `https://git.sadentel.net`.
+
+```html
+<iframe
+  src="https://render.sadentel.net/view/pcb/PCB_ID#token=READ_TOKEN"
+  width="100%"
+  height="800"
+  title="Altium design viewer"
+  loading="lazy"
+  referrerpolicy="no-referrer"
+  allowfullscreen
+></iframe>
+```