Routine subscription polls walked the entire post history every tick
even when nothing had changed, because gallery-dl's default `skip: True`
continues iterating archived posts. A creator with ~550 archived posts
(Knuxy patreon) saturates the 870s wall-clock cap before completing,
even with zero downloads needed. Plus, a tier-limited run that
downloaded hundreds of files but ran out the clock should be a
warning, not an error.
Two coupled changes, both operator-flagged 2026-06-01:
* **Tick mode (default, cron polls).** New `TICK_SKIP_VALUE = "exit:20"`
asks gallery-dl to exit after 20 contiguous archived items. Fresh
subscriptions + new-content cases still walk normally; established
subscription with zero new content exits in ~30s of HEAD requests
instead of pegging the timeout. 20 (not 5) gives headroom against
paywall warnings interleaving with archived items.
* **Backfill mode (explicit, operator-triggered).** Sticky for N runs
via new `Source.backfill_runs_remaining` (alembic 0031). While > 0,
downloads use `skip: True` + 1800s timeout. Auto-decrements per run
with early-reset to 0 when a clean run finds zero files (queue
drained). N defaults to 3 — multiple runs give the system enough
budget to finish a deep walk across timeout boundaries. New
`POST /api/sources/{id}/backfill` arms the source; "Deep scan"
button on each SourceRow (chip shows remaining count) wires it.
Plus partial-success classifier: non-zero gallery-dl exit + ≥1 file
downloaded + no source-level error fires `ErrorType.PARTIAL`, which
download_service maps to `status=\"ok\"`. The run did real work; the
next tick continues via gallery-dl's archive. No more red events for
"timed out mid-walk after downloading 300 files."
Retires `SourceConfig.skip_existing` — skip value is now derived from
the source state and passed as a separate `skip_value` parameter
through download() / _build_config_for_source(). `GD_DEFAULTS` drops
the now-dead key (was inert data after this refactor).
Tests cover:
* tick + backfill skip-value emission in _build_config_for_source
* PARTIAL classifier branch + TIER_LIMITED-wins-over-PARTIAL ordering
* SourceService.set_backfill_runs validation + persistence
* /api/sources/{id}/backfill 200/400/404 paths
* download_service auto-decrement / auto-reset / tick-mode-no-touch
* PARTIAL → status=ok in the orchestrator (no consecutive_failures bump)
Operator-requested 2026-05-27: centralize the per-platform quirks that
had been accumulating across credential_service, sidecar, and platforms
into a single per-platform module so adding/updating quirks becomes
"edit one file."
**Layout**
services/platforms/
base.py PlatformInfo dataclass + module-default key
chains + shared helpers (str_id_value, str_field)
__init__.py PLATFORMS dict + public API (auth_type_for,
known_platform_keys, to_dict,
external_post_id_keys_for, description_keys_for)
patreon.py metadata only — the reference platform, no quirks
subscribestar.py metadata + augment_cookies (18+ agreement) +
derive_post_url (synthetic /posts/<post_id>)
hentaifoundry.py metadata + augment_cookies (host-only PHPSESSID
duplicate) + derive_post_url (/pictures/user/...)
pixiv.py metadata + derive_post_url (/artworks/<id>)
discord.py metadata + derive_post_url
(channels/<server>/<channel>/<message>)
deviantart.py metadata only — un-audited; quirks to be added
when an operator first exercises DA
**PlatformInfo extensions**
Existing fields preserved. Four new optional fields:
external_post_id_keys: tuple[str, ...] | None
Override the sidecar external_post_id lookup chain. None falls
back to DEFAULT_EXTERNAL_POST_ID_KEYS in base.py
("post_id", "id", "index", "message_id") — covers every current
platform.
description_keys: tuple[str, ...] | None
Override the description body lookup chain. None falls back to
DEFAULT_DESCRIPTION_KEYS ("content", "description", "caption",
"message") — Discord's "message" body field is covered by the
default's trailing entry.
derive_post_url: Callable[[dict], str | None] | None
Synthesize the post permalink from sidecar metadata. None = trust
the bare `url` / `post_url` field (patreon, deviantart).
subscribestar/pixiv/hf/discord override this because their `url`
is the file CDN URL.
augment_cookies: Callable[[str], str] | None
Post-process the materialized cookies.txt before gallery-dl
consumes it. None = no-op. Used by subscribestar (age cookie) and
hentaifoundry (host-only PHPSESSID duplicate).
**Consumer changes**
- credential_service._augment_cookies(platform, netscape) shrunk from a
per-platform-conditional dispatcher (~80 lines of inlined helpers) to
a 5-line lookup: `info.augment_cookies(netscape) if info and
info.augment_cookies else netscape`. The platform-specific helper
bodies moved verbatim into the per-platform modules.
- sidecar.parse_sidecar similarly delegates: external_post_id chain via
external_post_id_keys_for(category), description chain via
description_keys_for(category), post_url via
PLATFORMS[category].derive_post_url. The _DERIVED_URL_PLATFORMS set
and inline _derive_post_url body both gone. Added a shared `_first_id`
helper for bool-safe id coercion.
**Public API preserved**
PLATFORMS, PlatformInfo, auth_type_for, known_platform_keys, to_dict
are all re-exported from the package's __init__.py. test_platforms_registry
test_credential_service, and test_sidecar_util pass without changes
because the behavior is identical; only the implementation moved.
**Adding a new platform**
1. Create services/platforms/<name>.py with `INFO = PlatformInfo(...)`
and any of the four optional hooks.
2. Import it in services/platforms/__init__.py + add to the PLATFORMS
tuple-comprehension.
3. Done. sidecar parsing, cookie materialization, /api/platforms all
pick it up automatically.
bvandeusen