docs: sync AGENTS with the shared fetch, download budget and inline answer

AGENTS.md

@@ -26,7 +26,7 @@ User-facing failure text is a function of the error class, never one generic sen
 
 The `/test <url>` command runs the ordinary link pipeline (`urls::url_media`) with `PostSend::Suppressed`: the media is sent and cached like any other link, but the chat's `forward_channel_id`/`edit_before_forward` are ignored, so a test never forwards to the channel and never opens the edit prompt (retries and dead-letter notifications behave as usual). `/test`, `/debug`, `/set_format` and `/clear_cache` use the custom `parse_arg_remainder` parser (whole remainder, trimmed) because teloxide's built-in `split` parser takes exactly one space-separated token per field: `/set_format <site> <format>` never parsed with it (and `/clear_cache` without an argument did not either), and a command that fails to parse falls through to the URL flow in silence. `commands::tests::every_documented_invocation_parses` pins every documented form against exactly that.
 
-The inline path (`handlers/inline.rs`) hands media URLs straight to Telegram, which fetches them itself and cannot send site-specific headers — so `x_media::site::needs_media_headers(url)` (true exactly where a site's `media_headers` is non-empty, i.e. pixiv's pximg.net) marks the media that must be skipped instead of shipped broken; locally produced media (ugoira MP4, bsky remux) fails `Url::parse` and is skipped the same way. Inline results are therefore URL-only by construction.
+The inline path (`handlers/inline.rs`) hands media URLs straight to Telegram, which fetches them itself and cannot send site-specific headers — so `x_media::site::needs_media_headers(url)` (true exactly where a site's `media_headers` is non-empty, i.e. pixiv's pximg.net) marks the media that must be skipped instead of shipped broken; locally produced media (ugoira MP4, bsky remux) fails `Url::parse` and is skipped the same way. Inline results are therefore URL-only by construction, and a query whose every item was skipped is answered *empty* (with a cache window) rather than left unanswered — an unanswered query keeps the client spinning and, through the debounce's release, re-runs the fetch on every keystroke.
 
 `url_media` is a thin wrapper over `url_media_inner`: `run_with_chat_action` sends the chat action, then re-sends it every `ACTION_REFRESH` (4 s) while the pipeline future is pending, because Telegram drops an action after ~5 s and a fetch (ugoira encode, HLS remux) plus an upload routinely outlasts that. The pipeline flips the shared `ActionHint` from `Typing` to `UploadPhoto`/`UploadVideo` once the media kinds are known. The `select!` is `biased` on the pipeline branch so a finished pipeline never emits a stray action.
 
@@ -36,13 +36,13 @@ The `x-media` library: `site::fetch(url)` dispatches through the `SITES` registr
 
 | Path | Purpose |
 |---|---|
-| `crates/x-media/src/` | Fetch library. `site/mod.rs` = dispatcher + `Fetched`/`FetchError`/`download_media*` (the streaming `download_media_to_file` and the capped `download_media_limited`, which is where a download's size is checked); `media.rs` = `Media` enum; `examples/fetch.rs` = end-to-end usage sample |
-| `crates/x-media/src/site/<twitter\|pixiv\|bsky\|misskey\|bilibili>/` | One directory per site: `mod.rs` (re-exports), `interface.rs` (PATTERN, `enabled()`, `fetch_from_url()`, `cache_key`/`is_retryable`/`media_headers`, unit struct `<Name>Site` implementing `site::Site`, `From<SiteStruct> for Fetched`), `model.rs` (serde DTOs). Pixiv adds `api.rs` (auth + transport); twitter adds `auth.rs` (logged-in GraphQL `TweetDetail` fallback for NSFW tweets, gated on `TWITTER_AUTH_TOKEN`; without the token a withheld tweet stays `FetchError::Sensitive` and the bot reports it as age-restricted instead of "no media"). Misskey targets misskey.io only (`POST /api/notes/show`, 400+`NO_SUCH_NOTE` → NotFound). Bilibili fetches dynamics (images/animated images only — an attached video degrades to its cover, and its title stands in for the post text, which AV dynamics do not have) from `/x/polymer/web-dynamic/v1/detail` sent with `features=itemOpusStyle` (without that flag the legacy serialization drops an image/text post's body and headline entirely — `desc` comes back `null`; the adapter still parses the legacy `major.draw`/`desc`/`archive` shapes as a fallback). No WBI signature is involved; device cookies `buvid3`/`buvid4` are fetched automatically from `/x/frontend/finger/spi` because bilibili's `-352` risk control starts rejecting plain requests, `BILIBILI_COOKIE` is the escalation when an IP stays blocked; `b23.tv` short links are deliberately unmatched. Twitter's `from_syndication_json` HTML-decodes the API text — syndication and GraphQL `full_text` both arrive pre-escaped (`&gt;` `&lt;` `&amp;` `&#39;`) — so the stored text is raw and the caption escap…
+| `crates/x-media/src/` | Fetch library. `site/mod.rs` = dispatcher + `Fetched`/`FetchError`/`download_media*` (the streaming `download_media_to_file` and the capped `download_media_limited`, which is where a download's size and its total time budget are enforced); `media.rs` = `Media` enum; `examples/fetch.rs` = end-to-end usage sample |
+| `crates/x-media/src/site/<twitter\|pixiv\|bsky\|misskey\|bilibili>/` | One directory per site: `mod.rs` (re-exports), `interface.rs` (PATTERN, `enabled()`, `fetch_from_url()`, `cache_key`/`is_retryable`/`media_headers`, unit struct `<Name>Site` implementing `site::Site`, `From<SiteStruct> for Fetched`), `model.rs` (serde DTOs). Pixiv adds `api.rs` (auth + transport); twitter adds `auth.rs` (logged-in GraphQL `TweetDetail` fallback for NSFW tweets, gated on `TWITTER_AUTH_TOKEN`; without the token a withheld tweet stays `FetchError::Sensitive` and the bot reports it as age-restricted instead of "no media"). Misskey targets misskey.io only (`POST /api/notes/show`, 400+`NO_SUCH_NOTE` → NotFound). Bilibili fetches dynamics (images/animated images only — an attached video degrades to its cover, and its title stands in for the post text, which AV dynamics do not have) from `/x/polymer/web-dynamic/v1/detail` sent with `features=itemOpusStyle` (without that flag the legacy serialization drops an image/text post's body and headline entirely — `desc` comes back `null`; the adapter still parses the legacy `major.draw`/`desc`/`archive` shapes as a fallback). No WBI signature is involved; device cookies `buvid3`/`buvid4` are fetched automatically from `/x/frontend/finger/spi` because bilibili's `-352` risk control starts rejecting plain requests, `BILIBILI_COOKIE` is the escalation when an IP stays blocked; `b23.tv` short links are deliberately unmatched. Twitter's `from_syndication_value` HTML-decodes the API text — syndication and GraphQL `full_text` both arrive pre-escaped (`&gt;` `&lt;` `&amp;` `&#39;`) — so the stored text is raw and the caption escap…
 | `crates/xmedia-bot/src/main.rs` | Entry point: env/log init, command registration (`register_commands` — `setMyCommands` plus the profile description texts), shared `send::BOT` force-init, startup sweep of this project's leftover temp files (`x_media::TEMP_FILE_PREFIX` + an age gate, since a killed process runs no destructors), startup repair of queued retries whose local media did not survive a restart (`handlers::repair_lost_local_media`, before any worker can lease: those rows are re-fetched from their `source_url`), queue worker start, site login validation (`site::validate_all`), `periodic_sweep` (`SWEEP_INTERVAL` 300 s): expired prompts are rewritten in place to `EDIT_PROMPT_EXPIRED_TEXT` with an empty keyboard — an edit, never a new message, so a background timer cannot wake a chat — plus the link-cache prune, the idle rate-limit buckets and the idle inline-query entries, and the queue backlog line (only when non-empty). Takes its collaborators rather than the statics so its loop is testable with a paused clock, dptree handler tree, webhook vs polling dispatch |
 | `crates/xmedia-bot/src/config.rs` | Manual env parsing into `Config` |
 | `crates/xmedia-bot/src/db.rs` | `DbPool`: one shared SQLite connection pool (`POOL_SIZE = 4`, WAL, busy_timeout) for all three tables over `$DATA_DIR/task_queue.db` (default `data/`) — the three stores share it; `open_store` creates file + schema and then applies the `PRAGMA user_version` migration chain (`MIGRATIONS` + `migrate` — append-only; `schema_init` is the version-0 baseline and must not gain columns an existing database would never receive — `db.rs`'s tests pin a pre-migration database upgrading intact, the shipped migration text frozen (appending is the only allowed change) and a fresh database landing at the latest version), `with_conn` runs all rusqlite I/O in `spawn_blocking` |
-| `crates/xmedia-bot/src/handlers/` | Handler modules: `mod.rs` (message entry point, `reply`, `log_key`, the group-only `GROUP_LINK_HINT` for a supported link posted outside a private chat), `commands.rs` (teloxide `BotCommands` enum + command executor, incl. `/test <url>` (send-only) / `/debug <url>` (parse-only) and the admin-only `/bot_dict` state dump; `/set_format` rejects unknown `{…}` placeholders and resets with `-`), `urls.rs` (URL extraction + bounded job channel (256) drained by `URL_WORKERS = 8` workers (`start_url_workers`) — backpressure instead of unbounded spawns; teloxide's per-chat workers are sequential — batch-forwards need concurrency; plus the startup repair `repair_lost_local_media`, whose decision (`needs_refetch`) and rewrite (`apply_refresh`) are pure and tested while the fetch itself is a live test), `inline.rs`/`callback.rs` (inline queries / edit-before-forward buttons, incl. `skip`; a forward that fails retryably is both queued *and* settles the prompt — the queued row carries the message ids itself, and a prompt left live let a second Confirm copy the same messages twice and let Skip answer "nothing was forwarded" while the row still delivered), `statics.rs` (global statics) |
-| `crates/xmedia-bot/src/state.rs` | `ChatStore`: parking_lot `Mutex<HashMap>` cache + SQLite write-through (`chat_state` table) |
+| `crates/xmedia-bot/src/handlers/` | Handler modules: `mod.rs` (message entry point, `reply`, `log_key`, the group-only `GROUP_LINK_HINT` for a supported link posted outside a private chat), `commands.rs` (teloxide `BotCommands` enum + command executor, incl. `/test <url>` (send-only) / `/debug <url>` (parse-only) and the admin-only `/bot_dict` state dump; `/set_format` rejects unknown `{…}` placeholders and resets with `-`), `urls.rs` (URL extraction + bounded job channel (256) drained by `URL_WORKERS = 8` workers (`start_url_workers`) — backpressure instead of unbounded spawns; teloxide's per-chat workers are sequential — batch-forwards need concurrency; one *shared* in-flight fetch per cache key (`fetch_shared`: a second chat, a batch forward or a retry asking for the same post meanwhile waits for the first caller's result, the entry is dropped the moment the fetch settles so nothing is ever answered from an old fetch, and a waiter whose sharer was cancelled fetches for itself); plus the startup repair `repair_lost_local_media`, whose decision (`needs_refetch`) and rewrite (`apply_refresh`) are pure and tested while the fetch itself is a live test), `inline.rs`/`callback.rs` (inline queries / edit-before-forward buttons, incl. `skip`; a forward that fails retryably is both queued *and* settles the prompt — the queued row carries the message ids itself, and a prompt left live let a second Confirm copy the same messages twice and let Skip answer "nothing was forwarded" while the row still delivered), `statics.rs` (global statics) |
+| `crates/xmedia-bot/src/state.rs` | `ChatStore`: parking_lot `Mutex<HashMap>` cache + SQLite write-through (`chat_state` table); the 300 s sweep's `prune_expired` evicts any chat with no live edit-before-forward prompt, so the cache (and the per-chat lock map) stays bounded to active prompts — durable settings reload from the DB on next use |
 | `crates/xmedia-bot/src/link_cache.rs` | `LinkCache`: SQLite-backed cache (`link_cache` table) of successfully sent posts — raw caption fields + Telegram `file_id`s; repeat links re-send locally (no fetch/upload), TTL + prune, invalidated on permanent send failure |
 | `crates/xmedia-bot/src/queue.rs` | `PersistentTaskQueue`: SQLite-backed queue (`tasks` table), `QUEUE_WORKERS = 4` concurrent workers (lease via `BEGIN IMMEDIATE` + `locked_until` TTL), retry→dead-letter, a `lease_token` fence: `lease_next` stamps a random token and every write-back (heartbeat, `delete`, `reschedule`, `mark_done`) is guarded by it, so a lease that expired and was re-leased cannot be written by its former holder — a lost lease stops the attempt instead; a finished row's `DELETE`/reschedule retried and a failed delete falling back to a `done` tombstone (the lease query and the sweep only look at `pending`/`in_progress`, so a task that already ran cannot be resurrected and re-run), `runnable_rows`/`replace_payload` (the startup repair's read/rewrite path: it runs before the workers exist, which is why it needs no lease token), `notify_one` worker wakeup plus a separate `Notify` for the 30 s lease-expiry sweep (a shared one let the sweep steal the workers' wakeup permit; the sweep does notify the workers after it actually recovered a row, since a recovered task is due immediately while every worker may be parked on `notify` with no pending row to sleep on), `busy_timeout` on all connections |
 | `crates/xmedia-bot/src/ctx.rs` | `AppContext`: the injected collaborators (`sender` + `ChatStore`/`PersistentTaskQueue`/`LinkCache`/`Config`), `from_statics` for production and the `CONTEXT` static the worker closures hold. `test_support::TestStores` backs handler tests with a tempdir store set, and the module also carries the fixtures those tests share — the canonical cached post (`cached_photo`), the edit-before-forward prompt (`seed_prompt` with its `PROMPT_ID`/`FORWARDED_ID`) and a scripted API error (`api_error`) — so no two test modules keep their own copies |