# Repository Guidelines

## Project Overview

Telegram bot (teloxide) that turns post links from X/Twitter, Pixiv, Bluesky, Misskey (misskey.io), and Bilibili dynamics into media messages (images, video, GIF) with the post's title, author, and tags. It supports batch media splitting, retry with persistence, inline queries, forward-channel rebinding with caption templates, and Pixiv ugoira→MP4 transcoding. README is in Chinese; user-facing bot strings are in English. The project is a Rust port of a Python predecessor (see `queue.rs` comments referencing `utils/task_queue.py`).

Two-crate Cargo workspace (both v1.9.1, edition 2024, resolver 3):

- **`crates/x-media`** — library that fetches and normalizes media from the four sites. Pure, no Telegram knowledge.
- **`crates/xmedia-bot`** — the bot binary: teloxide dispatcher, SQLite-backed chat state, persistent task queue.

## Architecture & Data Flow

```
Telegram update → Dispatcher (polling or axum webhook) → dptree branches
  ├─ message    → commands (any chat) / URL links (private chat only)
  ├─ inline_query → InlineQueryResult Photo/Video/Mpeg4Gif
  └─ callback_query → "forward" (copy to channel) / "template|<name>" (apply caption template)
```

Message flow: `message_handler` extracts URLs (from `url`/`text_link` entities, text + caption, deduped) → `x_media::site::fetch(url)` → `Fetched` → builds a `Task` → `send::send_media_sequence` (media groups ≤ 10, caption on first item) or `send::send_animation`. On Telegram URL-fetch failure or size error (`send_batch_via_upload`): download via `x_media::site::download_media` to a temp file (≤ 10 MiB), sniff magic bytes (`sniff_ext`), upload via multipart; oversized items fall back to `fallback_url`. On failure: `enqueue_retry` persists resume-state `Task` into the SQLite queue (it reports whether the row was really written, and only then does the user get the "retrying in Ns" notice — an enqueue that fails says so instead) → workers lease (120 s lock TTL) → retry with exponential backoff (≤ 30 s for the bot's own delays, `MAX_RETRIES = 2`) → dead-letter → `notify_failure`. Success → `post_send_actions`: edit-before-forward prompt with inline buttons, or `copy_messages` to the bound forward channel.

Debug command: `/debug <url>` runs the same `x_media::site::fetch` and replies with `debug_report` (`handlers/commands.rs`) — site id, normalized cache key, source URL, title/author/tags, sensitive flag, caption and the media list — nothing is sent, cached or forwarded; the report is capped at 4000 chars and sent with HTML parse mode: raw fields are escaped, and the caption is wrapped in a `<blockquote>` so it renders exactly like the sent media caption (escaped text and links included). The caption it shows is `preview_caption`'s: the chat's per-site format override plus the long-post quoting, i.e. exactly what the send paths produce — showing the raw built-in caption made `/set_format` look like a no-op, and the `/set_format` success reply points users at `/debug` to preview.

User-facing failure text is a function of the error class, never one generic sentence: `urls::fetch_error_message` maps `FetchError::NotFound` (post gone), `Sensitive` (withheld, needs `TWITTER_AUTH_TOKEN`), `Blocked` (source risk control), `Disabled { site }` (a registered site switched off — pixiv without a token, the one case `fetch` answers `Err` instead of `Ok(None)`) and `Transient`/`Http` (source down) apart. The same distinction drives the group hint: a supported link posted in a group (not a channel) gets one `GROUP_LINK_HINT` reply, because the link pipeline is private-chat only.

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, 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.

The `x-media` library: `site::fetch(url)` dispatches through the `SITES` registry (per-site `impl Site`, in order twitter → bsky → misskey → pixiv → bilibili) and returns `Ok(None)` for unmatched URLs (`Err(FetchError::Disabled { site })` when the URL matches a registered site whose `enabled()` is false — see `disabled_site`). `Fetched { source_url, caption, title, content, media: Vec<Media>, sensitive, site_id, … }` (title and content are split per platform: a pixiv artwork's title and description, a bilibili headline and body, and text-only posts whose text is all `content`); `caption_with(format)` substitutes `{url} {author} {author_url} {title} {content} {tags}`.

## Key Directories

| 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 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; 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 + the source media URLs + Telegram `file_id`s; repeat links re-send locally (no fetch/upload), TTL + prune; a permanent send failure *degrades* the entry instead of dropping it (the file ids go, the URLs stay, so the next request re-sends from those without a fetch), and a degraded entry that fails again is removed |
| `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 |
| `crates/xmedia-bot/src/send/` | `send/mod.rs`: `Task`/`MediaItemPayload` payloads, `SendError`/`Classification`, `send_media_sequence`/`send_animation`/`forward_messages`; `send/input_media.rs`: payload → `InputFile`/`InputMedia` + `build_media_group` (caption on the first item only); `send/upload.rs`: the download-and-reupload fallback (`prepare_upload_item`/`send_batch_via_upload`, photo downscale handoff); `send/post_send.rs`: link-cache write, `KEEP_ALIVE` registry, `settle_task`, `post_send_actions`, `handle_task`/`dead_letter_notify` |
| `crates/xmedia-bot/src/media_sender.rs` | `MediaSender` trait: the user-flow surface (`send_media_group`/`send_animation`/`copy_messages`/`send_message`/`answer_callback_query`/`edit_message_text`/`edit_message_caption`/`delete_message`/`send_chat_action`) implemented by teloxide `Bot` (per-chat rate-limited) and by a recording `MockSender` in tests. Admin/setup APIs (`get_chat`, `set_my_commands`, …) stay on the concrete `Bot`. `test_support` holds the scripted `MockSender` and `fake_api` (the stand-in API the real-`Bot` tests drive) |
| `crates/xmedia-bot/src/rate_limit.rs` | Two token buckets paced before sends reach the API so batch forwards don't trip flood control: one per chat (`CAPACITY = 20`, ~20 msg/min refill) and one bot-wide (`acquire_global`, 30/s — Telegram's per-bot ceiling, invisible to any per-chat bucket and only binding when a batch fans out over many chats). `prune_idle` drops the per-chat buckets that refilled while unheld |

## Development Commands

```bash
export TELOXIDE_TOKEN=<token>          # required; PIXIV_REFRESH_TOKEN optional (Pixiv disabled without it)
cargo run -p xmedia-bot                # run the bot (polling by default)
cargo run -p x-media --example fetch -- <url>   # test a link through the fetch library
cargo test --workspace                 # full test suite (no CI test step exists — run locally)
cargo build --release -p xmedia-bot    # release build (Dockerfile does this)
cargo clippy --workspace --all-targets # lint (Clippy is the configured IDE linter)
cargo fmt --check                      # formatting
```

Docker: `docker build -t tgxmb .` then `docker run --rm -d --name tgxmb --env-file .env -v ./data:/app/data tgxmb`. Runtime requires **ffmpeg** (built into the image). The builder fetches crates.io + ffmpeg; on restricted networks pass proxy build args, e.g. `--build-arg HTTP_PROXY=http://host.docker.internal:10808 --build-arg HTTPS_PROXY=…` (Docker Desktop builds can't reach the host loopback — use `host.docker.internal`).

## Code Conventions & Common Patterns

- **Errors via `thiserror` derive** (no anyhow): the public, stringified errors — `FetchError` (`Http`/`Json`/`Pixiv`/`Site`/`NotFound`/`Blocked`/`Disabled`/`Sensitive`/`TooLarge`/`MediaPrep`/`Transient`/`Io`) and `PixivError` — derive `thiserror::Error` with `#[from]` conversions; `Display`/`source()` come from the derive. The internal control-flow enums — `QueueError` (`Retryable { delay_seconds, payload }` / `Permanent`), `SendError` (Retryable/Permanent), `Classification`, `FallbackError` — carry no `Display` and are handled by direct variant matching. New errors should follow the same split: stringified/public errors derive `thiserror`, internal flow enums stay plain.
- **Global state via `std::sync::LazyLock` statics**, not DI: `CONFIG`, `CHAT_STORE`, `TASK_QUEUE` in `handlers/statics.rs`; shared reqwest `CLIENT` in `x-media/src/site/mod.rs`. `Bot` is passed/cloned into handlers; queue workers share the process-wide `send::BOT` (`LazyLock<Bot>`, force-initialized in `main` so a missing token fails at startup).
- **Async**: tokio multi-thread runtime (`#[tokio::main]` default). All rusqlite I/O inside `tokio::task::spawn_blocking`. Long loops use `tokio::select!` with `tokio::sync::{watch, Notify}` stop/wake channels. No streams.
- **Blocking sync primitives**: `parking_lot::Mutex` for hot caches, `tokio::sync::Mutex` for async-shared state (pixiv token cache), `AtomicBool` for feature gates.
- **Site adapter convention**: each site module exports `PATTERN: LazyLock<Regex>`, `enabled() -> bool`, `fetch_from_url(url) -> Result<Fetched, FetchError>`, plus `cache_key`/`is_retryable`/`media_headers`, and a unit struct `<Name>Site` implementing `site::Site`; the central dispatcher (`site/mod.rs`) only iterates the `SITES` registry. Adding a site = new `site/<name>/{mod.rs,interface.rs,model.rs}` + one `Box::new(...)` entry in `SITES` — the bot crate never lists sites (SetFormat whitelist, cache-key site lookup and startup validation all derive from the registry). Async trait methods return `SiteFuture` (a boxed `Pin<Box<dyn Future + Send>>`) because `async fn` in traits is not dyn-compatible.
- **Serde**: per-site `model.rs` are pure `Deserialize` DTOs mirroring API JSON; site structs in `interface.rs` have private fields, a `caption()` builder, and `impl From<SiteStruct> for Fetched`. Persisted payloads use internally-tagged enums (`#[serde(tag = "kind")]` / `type`).
- **Naming**: module-per-concern, snake_case files, `CamelCase` types, `snake_case` fns. `//!` module docs and `///` docs on non-obvious logic (syndication token, ugoira encoding, `display_text_range`).
- **Retries**: only `x-media::site::fetch` retries (3 attempts, `1 << attempt` backoff, HTTP errors only); `site::fetch_once` is the same code path with a single attempt, used by inline queries whose answer window is shorter than the backoff. A status a site answers with is classified by what a *retry* can change: 404/410 are `NotFound` and 401/403 are `Blocked` (permanent, reported at once), 429/5xx are `Transient` and retried. Queue retries are explicit `QueueError::Retryable` with computed delay (`retry_delay_seconds`), scaled per attempt by `scaled_retry_delay` — which only ever scales **up**, so a delay the server asked for (Telegram `retry_after`) is never shortened. `send::classify_request_error` is the send-side counterpart: `RetryAfter` and `Network` are retryable, and so is a 5xx — teloxide sleeps 10 s on a server error and then parses the body, so by then the HTTP status is gone and the condition is recognised by shape instead (a JSON server-error description, or an `InvalidJson` whose raw body is not JSON, i.e. a proxy/error page).
- Logging via `log` macros (`pretty_env_logger`, level from `RUST_LOG`). `main.rs` initializes the **timed** builder with a default filter of `info,hyper_util=warn,reqwest=warn` when `RUST_LOG` is unset: the plain `init` had no timestamps and fell back to `error`, so a deployment that forgot the variable logged nothing at all, and at `debug` the HTTP client's own lines outnumbered the bot's two to one. An explicit `RUST_LOG` overrides the default wholesale. Level convention: `info` = lifecycle + per-post business results (`sent`/`forwarded`/`copied`, with `chat=` and the total `ms`), admin/operator actions and anomalies (fallback, retry enqueue, dead-letter is `error`); `debug` = per-request detail (URL extraction, `fetching`/`fetched` with the fetch duration, batch sends, queue processing with the row's `chat=`/`key=` and per-attempt `ms`, photo processing, inline queries); `trace` = user data (the full URL, the message text, the inline query). At `debug` and above links are printed via the normalized cache key (`handlers::log_key`, e.g. `[key=twitter:123...]`), so a `debug` log can be shared without echoing what users pasted, and degradations that leave the user served (a failed cache read/write, a failed chat action) are `warn`, not `error`. The only queue/sweep aggregate is the 300 s sweep's queue line, and it speaks only when the queue is non-empty.

## Important Files

| File | Why it matters |
|---|---|
| `crates/xmedia-bot/src/main.rs` | Startup sequence, webhook vs polling, graceful shutdown (SIGINT via teloxide ctrlc / SIGTERM via `stop_token` for docker, → sweep stop → admin msg → queue stop) |
| `crates/xmedia-bot/src/handlers/` | `statics.rs` = `CHAT_STORE`/`TASK_QUEUE`/`CONFIG` singletons (open `$DATA_DIR/task_queue.db`, default `data/` **relative to CWD**, dir auto-created); `mod.rs` also holds `apply_caption_edit`, the one place a caption edit is applied and its failure classified: a short retryable delay is retried once, anything else is reported to the user instead of being swallowed (`callback.rs`'s template button answers its toast with the failure and leaves the record alone); `commands.rs` = command dispatch (incl. `/test <url>` send-only, `/debug <url>` parse-only, the read-only `/settings` every chat member can read — unlike the admin-only `/bot_dict` raw dump — and template removal; `/start`/`/help` carry the guidance teloxide's `descriptions()` cannot render, and `/set_format` rejects unknown `{…}` placeholders, resetting with `-`); `urls.rs` = URL extraction + the per-URL pipeline (`url_media` takes a `PostSend` mode: chat settings vs `/test`'s suppressed actions); `inline.rs` = debounced inline queries (hotlink-protected and local media skipped); `callback.rs` = edit-before-forward buttons (dptree entry + testable `handle_callback` core, incl. `skip`) |
| `crates/xmedia-bot/src/send/` | `mod.rs`: constants `MAX_MEDIA_GROUP = 10`; `classify_request_error` (5xx/non-JSON bodies retry, see the Retries bullet) and the media-fetch markers that route a URL send into the reupload fallback — including `failed to get HTTP url content`, the description single-media URL sends answer with; the senders. `upload.rs`: download-and-reupload fallback triggered only by Telegram API errors (`is_media_fetch_failure` / `is_size_error`), with a download's class from `classify_download_error` (transport/429/5xx retry; 4xx is permanent — the media itself is gone or refused — and a temp-file *write* failure retries, being resource exhaustion far more often than a broken temp dir). Item preparation is bounded **process-wide** (`PREP_SLOTS` in `upload.rs`: URL workers and queue workers can each be inside a batch, so a per-batch bound is not a memory bound), and the check that routes an oversized item to `fallback_url` is the download's own declared-Content-Length abort (`FetchError::TooLarge` → `MediaTooLarge`) — there is no separate size probe, which used to cost a second request per item. `post_send.rs`: settlement (`settle_task`), cache write, post-send actions (dead-letter text via `failure_text`: post key + cause, since the raw error alone does not say which link died), queue handlers. `input_media.rs`: payload → `InputMedia` |
| `crates/xmedia-bot/src/photo.rs` | Pure-Rust photo processing (no ffmpeg): `png` (image-png) decode/encode + `zune-jpeg` decode + `fast_image_resize` Lanczos3 downscale + `jpeg-encoder`. Photos over Telegram's limits (width + height > 10000 px → `PHOTO_INVALID_DIMENSIONS`; bytes > 10 MiB) are decoded, downscaled keeping the format, PNG bit depth > 24 (RGBA 32-bit / 16-bit per channel) reduced to 24-bit RGB with alpha flattened white (≤24-bit untouched, never upconverted), and transcoded to JPEG only if still over the cap; memory budget guarded, otherwise the item's smaller fallback URL. Two budgets, not one: `MAX_PHOTO_DOWNLOAD_BYTES` (32 MiB) caps the *download* in the send fallback — the whole body is buffered, once per prep slot — while `MAX_DECODE_BYTES` (512 MiB) stays the pre-allocation guard that decides whether a decoded photo can be processed at all; over either one the item degrades to its smaller URL |
| `crates/x-media/src/site/mod.rs` | Dispatcher, `Fetched`/`FetchError`, shared `CLIENT`, `download_media` (adds `Referer: https://www.pixiv.net/` for `pximg.net` hotlink protection), `needs_media_headers` (the same per-site rule, asked by the inline path to skip what Telegram cannot fetch) |
| `crates/x-media/src/site/pixiv/api.rs` | OAuth token exchange (hardcoded app client id/secret), access-token cache, ugoira zip→MP4 via ffmpeg in `spawn_blocking` |
| `Dockerfile` | Multi-stage: cached dep layer via stub sources + `touch *.rs` mtime bump (cargo's freshness is mtime-based and `cargo clean -p` removes 0 files — the touch is what forces the real sources to rebuild while deps stay cached), static ffmpeg from ffmpeg.martin-riedl.de (`FFMPEG_URL` arg, optional `FFMPEG_SHA256` checksum, `unzip -t` integrity check), `debian:bookworm-slim` runtime, entrypoint. Runtime ships **no libssl/libcrypto/CA bundle** — rustls webpki-roots handles all TLS, and the static ffmpeg only processes local files (downloads go through reqwest) |
| `docker-entrypoint.sh` | Privilege drop: `useradd` with `LOCAL_USER_ID` (default 9001) + `setpriv` (no gosu on bookworm-slim) |
| `docker-compose.yml` | The deployment composition, committed as-is: every instance value (token, admins, site credentials, domain) is a `${VAR}` substitution read from the gitignored `.env` beside it, so the file needs no per-deployment edit — and a variable not listed in a service's `environment:` never reaches that container. Ships nginx-proxy + acme-companion: webhook mode needs TLS termination in front (teloxide's axum listener is HTTP-only; `WEBHOOK_CERT` only feeds `set_webhook`), bot exposes `VIRTUAL_HOST`/`VIRTUAL_PORT` on the shared `proxy` network, no host port; container names `nginx-proxy`/`acme-companion`/`tgxmb`, start order via `depends_on` (proxy → acme → bot) |
| `.github/workflows/docker.yml` | CI: build+push to Docker Hub on tag `v*`/master, plus a build-only check on PRs touching the build inputs; **no test step**; verifies a release tag matches both crate versions; buildx gha cache (`cache-from` always, `cache-to` except on PRs, scope `tgxmb-build`, `mode=max`) so cargo deps + ffmpeg layers are restored across runs; `FFMPEG_URL`/`FFMPEG_SHA256` come from repo variables when set |
| `README.md` | Feature docs + command table (Chinese) |

## Runtime/Tooling Preferences

- **Rust, stable, edition 2024**, workspace resolver 3. No `rust-version`/MSRV pin, no `rust-toolchain.toml` — recent stable is assumed. No nightly features.
- Package manager: **Cargo** (workspace with path dep `x-media` ← `xmedia-bot`). No `[workspace.package]`/shared deps — each crate lists deps independently.
- **TLS is rustls end-to-end** (no native-tls/openssl in the tree, no libssl in the Docker runtime image): `teloxide` is declared `default-features = false` with `["webhooks-axum", "macros", "rustls", "ctrlc_handler"]` (the removed `default` also carried `native-tls` and `ctrlc_handler` — the latter must stay); x-media's reqwest is `default-features = false` with `["json", "rustls-tls", "gzip", "http2"]` (webpki-roots baked in, so the image ships no CA bundle; `gzip` because the site APIs answer their JSON compressed — twitter's syndication body is 4469 bytes identity vs 1066 gzipped — and `http2` because every site CDN here negotiates h2). One reqwest 0.12.28 in the lock.
- **Versioning**: bump the version in all three places (`crates/x-media/Cargo.toml`, `crates/xmedia-bot/Cargo.toml`, `Cargo.lock`) and **keep `README.md`, `README.en.md` and `AGENTS.md` in sync with the code on every bump**, then commit (`chore: bump version to X.Y.Z`), create an annotated tag `vX.Y.Z`, and push branch + tag **in one push** (`git push origin master vX.Y.Z`; the tag push triggers the Docker Hub build). Pushing them separately with the branch first makes the master run of `docker.yml` build the same commit as the tag run — its duplicate check can only see the tags that already exist on the remote. The tag must equal both crate versions: `.github/workflows/docker.yml` verifies that before building, and `--locked` verifies the lock file.
- Config is **environment-variable driven** (dotenv loads `.env`, which is gitignored; `.env.example` is the tracked template — `cp .env.example .env` — and is also the file `docker compose` substitutes `${VAR}` from, so every variable the compose passes must be documented there). Key vars: `TELOXIDE_TOKEN` (required), `PIXIV_REFRESH_TOKEN`, `TWITTER_AUTH_TOKEN` (optional; x.com `auth_token` cookie — enables the logged-in GraphQL fallback that fetches NSFW tweets syndication withholds), `BILIBILI_COOKIE` (optional; whole bilibili cookie string — bilibili dynamics fetch anonymously and add their own device cookies, this only rescues an egress IP that bilibili has hard-flagged with `-352`/412), `BOT_ADMIN` (comma-separated ids), `EDIT_MESSAGE_TTL_SECONDS` (default 86400), `LINK_CACHE_TTL_SECONDS` (default 604800), `CAPTION_QUOTE_TEXT_CHARS` (default 200; a post whose text — the `title` plus `content` joined, see `site::compose_text` — reaches this length gets that text wrapped in an expandable blockquote inside its caption, the URL and author line staying outside; `0` disables it. Applied at the send boundary in `send::quote_long_caption`, which locates the text as what follows the author link, so a `/set_format` that moves `{title}`/`{content}` elsewhere and pixiv's title-inside-a-link layout opt out; `copy_messages` forwards and queued retries inherit the wrap, while the edit-before-forward rewrite stays unquoted by design), `DATA_DIR` (default `data`, CWD-relative; the SQLite dir, auto-created), `WEBHOOK`/`WEBHOOK_URL`/`WEBHOOK_LISTEN`/`WEBHOOK_PORT`/`WEBHOOK_CERT`/`WEBHOOK_SECRET_TOKEN` (webhook mode requires URL/listen/port, `.expect`ed; `WEBHOOK_CERT` is Telegram-facing self-signed validation only — TLS must be terminated by a reverse proxy), `RUST_LOG`, `TELOXIDE_PROXY`, `LOCAL_USER_ID` (entrypoint only).
- SQLite via `rusqlite` with `bundled` feature (no system libsqlite needed). DB file `$DATA_DIR/task_queue.db` (default `data/task_queue.db`, CWD-relative — run from the workspace root, or `/app` in Docker; set `DATA_DIR` to pin state anywhere). Mount `./data` and `./cert` volumes.
- `.gitattributes` enforces LF for `*.sh` (CRLF breaks shebangs in containers). `.gitignore`: `.env`, `data/`, `cert/`, `nginx-*` (proxy state), `/target`, `.idea/` (the compose file is tracked; only `.env` carries the deployment's own values).
- Docs are in Chinese (README, AGENTS.md); user-facing bot strings are in English. Keep that split when editing user-facing strings and docs.

## Testing & QA

- **~180 tests, all inline `#[cfg(test)] mod tests`** — no `tests/` integration directories. Framework: built-in Rust test + `#[tokio::test]` (dev-deps only in `x-media`: tokio macros/rt-multi-thread, dotenv).
- No mocking framework anywhere (no mockito/wiremock/mockall). Conventions: pure-function units (regex parsing, serde round-trips, chunking, retry math) tested synchronously; async tests use real dependencies — file-backed SQLite via `tempfile` (`queue.rs::new_queue()` helper), live network fetches. Tests that must go through a **real `Bot`** (its URL/multipart building, the per-chat limiter and the bot-wide budget) talk to a stand-in API instead (`media_sender::test_support::fake_api::FakeApi`, a `tokio` TCP listener that records every call and answers the smallest result each method needs — teloxide keys methods by payload type, so the recorded name is `SendMediaGroup`, not `sendMediaGroup`): a media group, the edit-before-forward prompt through the real callback path, and `handlers::handle_message` (the context-taking body of `message_handler`, split out for exactly this).
- Live-network tests exist in `site/twitter/interface.rs` (5), `site/bsky/interface.rs` (1), `site/misskey/interface.rs` (1), `site/bilibili/interface.rs` (5), `site/pixiv/api.rs` (1); `photo.rs` adds one `#[ignore = "heavy: …"]` test. `site/mod.rs` also has a **token-gated but not `#[ignore]`d** pixiv download test (`download_media_pixiv_original_with_referer`): it hits `i.pximg.net` whenever `PIXIV_REFRESH_TOKEN` is set, so a local `cargo test --workspace` is not fully offline and can flake on a pixiv CDN body timeout. `disabled_site_is_reported_not_ignored` (same file) is gated the other way round: it asserts `fetch` answers `FetchError::Disabled { site: "pixiv" }` for a pixiv link and early-returns when `PIXIV_REFRESH_TOKEN` **is** set (the site is then enabled). Test gating convention (enforced by `.github/workflows/ci.yml`): pure unit tests always run; live-network tests carry `#[ignore = "live network: ..."]` (run via `cargo test --workspace -- --ignored live`); token-gated pixiv tests early-return when `PIXIV_REFRESH_TOKEN` is absent **or empty** (an unset GitHub secret arrives as `""` — `is_err()` alone would run them tokenless and fail), and the bilibili live tests early-return when the API answers risk control (`-352`, which bilibili applies per IP by request volume). Run the full offline suite with `cargo test --workspace`.
- Fixtures are inline `serde_json::json!` builder fns (`fixture()`, `thread_json()`, `illust_json()`), not files. The shared `CLIENT` sets `pool_max_idle_per_host(0)` under `#[cfg(test)]` to avoid cross-runtime `DispatchGone`.
- **CI** — `.github/workflows/ci.yml` (actions pinned to commit SHAs, `--locked` on every cargo invocation, `concurrency` cancels superseded runs, `RUST_BACKTRACE=1`) runs (behind a `changes` gate job, so a push/PR whose entire diff is markdown skips it instead of burning four minutes on nothing) `cargo fmt --check` + `cargo clippy --workspace --all-targets --locked -- -D warnings` + `cargo test --workspace --locked` + a release-profile `cargo build --release --locked` + an `actions-rust-lang/audit` dependency-vulnerability gate (offline, no secrets, on every push/PR) and a `live` job (schedule/manual/tag only, `-p x-media` since every network/secret-gated test lives there, `continue-on-error`) for the `#[ignore]`d live + token tests. `.github/workflows/docker.yml` builds and pushes the image on master/tag and runs a **build-only check on pull requests touching the build inputs**; its `should-build` gate skips a branch push that is already tagged (`git tag --points-at` — the tag run builds it, so push both refs together) or that touched no build input at all, while a tag push always builds (`Dockerfile`, entrypoint, manifests, `.dockerignore`); a release tag must match both crate versions or the build stops, and `FFMPEG_URL`/`FFMPEG_SHA256` are taken from repository variables when set (a release can pin an exact ffmpeg build). `.github/dependabot.yml` keeps crates, the pinned actions and the Docker base images current.
- Untested and hard to test without a mock seam: `config.rs`, `handlers/statics.rs`; `db.rs` is covered for the migration chain but not for pool behaviour under contention; `main.rs` is covered where it was split out (`periodic_sweep`, `sweep_temp_dir`) but not for startup/shutdown or its `dptree` branch tree (the handlers themselves are, through the stand-in API); in `x-media`: `media.rs`, `lib.rs`, all `model.rs`. The `commands.rs` *executor* needs a real `Bot` (only its pure report builder is tested). Everything else — `handlers/{mod,callback,inline,urls}.rs`, `send/*`, `ctx.rs`, `state.rs`, `queue.rs`, `link_cache.rs`, `rate_limit.rs` — is driven through `TestStores`/`ctx::test_support` and the scripted `MockSender`.
- No coverage tracking.