fix(scheduler,i18n): a failure a job names reads in the reader's language

The audit log showed a failed RSS poll as the server's English sentence
under a Hungarian UI. A job can now raise progress.JobFailed(reason,
message, **params): the scheduler stores the reason and params as the
run's data (dashboard, manual-run notice, audit row) beside the English
line, and the client renders scheduler.failure.<reason>. The RSS outage
names its first channel and the reason code (HTTP 404 vs unreachable).
An upstream's own error text stays as raised (diagnostic).

backend/app/progress.py

@@ -24,6 +24,19 @@ def report(current: int, total: int | None = None, phase: str | None = None) ->
         sink(current, total, phase)
 
 
+class JobFailed(RuntimeError):
+    """A job's own failure, said so the reader's language can name it (E31): the client reads
+    `scheduler.failure.<reason>` and interpolates `params` (keep them to values the reader may see —
+    numbers, ids, short codes). The message is the English line the log and `last_error` keep. An
+    upstream's own error (a timeout, a refused connection) is not one of these: it stays as raised,
+    being diagnostic."""
+
+    def __init__(self, reason: str, message: str, **params: object):
+        super().__init__(message)
+        self.reason = reason
+        self.params = params
+
+
 class bind:
     """Context manager that binds a progress sink for the duration of a job run."""
 

backend/app/scheduler.py

@@ -231,17 +231,22 @@ def _job(name: str, fn) -> None:
         db.rollback()
         log.exception("job %s failed", name, extra=logs.event("scheduler.job.failed", job=name))
         err = str(exc) or exc.__class__.__name__
+        # A failure the job named (progress.JobFailed) rides along as data, as a result does, so the
+        # client says it in the reader's language; `err` stays the English line.
+        failure = (
+            {"failure": exc.reason, **exc.params} if isinstance(exc, progress.JobFailed) else None
+        )
         _record(
             name,
             status="error",
             last_finished=_now_iso(),
             last_error=err,
-            result=None,
+            result=failure,
             progress=None,
         )
         if actor_id is not None:
-            _notify_done(db, actor_id, name, "error", err)
-        _audit_run(db, actor_id, name, "error", err, None)
+            _notify_done(db, actor_id, name, "error", err, failure)
+        _audit_run(db, actor_id, name, "error", err, failure)
     finally:
         # ALWAYS release the claim, even if the body raised before its own status update — so a
         # failure can never wedge the job as permanently "running".

backend/app/sync/runner.py

@@ -83,6 +83,8 @@ def run_rss_poll(db: Session, channels: list[Channel] | None = None) -> dict[str
     # outage from one permanently dead feed id — which is the whole difference on an instance with
     # a single subscription, where BOTH render as 100% failed.
     first_error: str | None = None
+    # The same first failure as data, for the reader's language: whose feed, and why (`reasons`' key).
+    first_failure: tuple[str, str] | None = None
     # What failed, as counts per reason (`http_404`, `transport`, `apply`, …) plus a few examples —
     # the ONE warning a poll writes. One line per failed channel was what turned YouTube's RSS outage
     # of 2026-09-16 into 11k warnings in four hours; each channel's own line is DEBUG now.
@@ -92,18 +94,19 @@ def run_rss_poll(db: Session, channels: list[Channel] | None = None) -> dict[str
     # hand the same rows to the same broken write) — the feed fallback's candidates.
     unread: list[str] = []
 
-    def fail(reason: str, detail: str, *, unexpected: str | None = None) -> None:
+    def fail(reason: str, channel_id: str, detail: str, *, unexpected: str | None = None) -> None:
         """Count a channel that did not get polled. `unexpected` is the message for a failure that
         is a bug on our side: its FIRST occurrence per reason gets a traceback at ERROR, the rest
         DEBUG — a read-only database fails every channel the same way, and 979 identical tracebacks
         tell nobody anything the first one didn't. Call it from inside the `except` block."""
-        nonlocal failed, first_error
+        nonlocal failed, first_error, first_failure
         if unexpected is not None:
             level = logging.ERROR if reasons[reason] == 0 else logging.DEBUG
             log.log(level, unexpected, exc_info=True)
         failed += 1
         reasons[reason] += 1
         first_error = first_error or detail
+        first_failure = first_failure or (channel_id, reason)
         if len(examples) < RSS_FAILURE_EXAMPLES:
             examples.append(detail)
 
@@ -125,13 +128,16 @@ def run_rss_poll(db: Session, channels: list[Channel] | None = None) -> dict[str
             # bug on our side and earns a traceback (the first of its kind per poll).
             except RssError as exc:
                 log.debug("RSS poll skipped for channel %s: %s", channel.id, exc)
-                fail(exc.reason, f"{channel.id}: {exc}")
+                fail(exc.reason, channel.id, f"{channel.id}: {exc}")
                 unread.append(channel.id)
             # silent-ok: `fail(unexpected=…)` is the report — it logs at ERROR with the
             # traceback, once per reason per poll, which is the flood control this loop needs.
             except Exception as exc:  # noqa: BLE001 — one channel must not stop the poll
                 fail(
-                    "error", f"{channel.id}: {exc}", unexpected=f"RSS fetch failed for {channel.id}"
+                    "error",
+                    channel.id,
+                    f"{channel.id}: {exc}",
+                    unexpected=f"RSS fetch failed for {channel.id}",
                 )
             else:
                 try:
@@ -144,6 +150,7 @@ def run_rss_poll(db: Session, channels: list[Channel] | None = None) -> dict[str
                     db.rollback()
                     fail(
                         "apply",
+                        channel.id,
                         f"{channel.id} (apply): {exc}",
                         unexpected=f"RSS apply failed for {channel.id}",
                     )
@@ -180,9 +187,17 @@ def run_rss_poll(db: Session, channels: list[Channel] | None = None) -> dict[str
         # "fix this subscription"; `Connection refused` says "the egress is down".
         # The fallback's count rides along: a red card during an RSS outage should still say
         # whether the uploads are arriving another way.
-        raise RuntimeError(
+        # As data too (E31): the audit log and the inbox say it in the reader's language, the first
+        # failure as its channel and its reason code (`http_404` vs `transport` is that difference).
+        first_channel, first_reason = first_failure or ("", "error")
+        raise progress.JobFailed(
+            "rss_all_failed",
             f"RSS poll failed for all {total} channels — first: {first_error}"
-            f" (read through the API instead: {fallback['read']})"
+            f" (read through the API instead: {fallback['read']})",
+            total=total,
+            channel=first_channel,
+            cause=first_reason,
+            read=fallback["read"],
         )
     return {"new": new + fallback["new"], "failed": failed, "fallback": fallback["read"]}
 

backend/tests/test_scheduler.py

@@ -86,3 +86,31 @@ def test_a_job_runs_audit_row_carries_its_result_as_data(db):
         {"status": "skipped", "summary": "sync paused", "result": {"skipped": "sync paused"}},
         {"status": "error", "summary": "boom"},
     ]
+
+
+def test_a_failure_the_job_names_rides_along_as_data(db, make_user):
+    """E31: a failed RSS poll reached the Hungarian audit log as the server's English sentence. A
+    failure the job names (`progress.JobFailed`) is stored as data beside that sentence — on the
+    dashboard, the manual-run notice and the audit row — so the client says it in the reader's
+    language. Any other failure keeps only its own text (the test above)."""
+    from app import progress
+    from app.models import AuditLog
+
+    def outage(_db):
+        raise progress.JobFailed("rss_all_failed", "RSS poll failed", total=2, cause="transport")
+
+    admin = make_user("failure@example.com", role="admin")
+    token = scheduler._manual_actor.set(admin.id)
+    try:
+        scheduler._job("rss_poll", outage)
+    finally:
+        scheduler._manual_actor.reset(token)
+
+    named = {"failure": "rss_all_failed", "total": 2, "cause": "transport"}
+    rss = _snapshot_job("rss_poll")
+    assert rss["last_error"] == "RSS poll failed"
+    assert rss["result"] == named
+    notice = db.execute(select(Notification).where(Notification.user_id == admin.id)).scalar_one()
+    assert notice.data["result"] == named
+    row = db.execute(select(AuditLog).order_by(AuditLog.id.desc())).scalars().first()
+    assert row is not None and row.after["result"] == named

backend/tests/test_sync_guards.py

@@ -6,6 +6,7 @@ import logging
 import httpx
 import pytest
 
+from app import progress
 from app.sync import runner
 from app.sync.playlists import FAILED, _Breaker
 from app.sync.subscriptions import should_prune
@@ -224,8 +225,15 @@ class TestRssPollResult:
         def dead(cid):
             raise rss.RssError(f"RSS fetch for {cid} returned HTTP 404", "http_404")
 
-        with pytest.raises(RuntimeError, match="HTTP 404"):
+        with pytest.raises(RuntimeError, match="HTTP 404") as err:
             self._run(monkeypatch, fetch=dead, apply_=lambda db, ch, e: 1, channels=("UC_dead",))
+        # E31: and as data, for the reader's language — whose feed, and the reason code that tells a
+        # dead feed (`http_404`) from a dead egress (`transport`).
+        assert isinstance(err.value, progress.JobFailed)
+        assert (err.value.reason, err.value.params) == (
+            "rss_all_failed",
+            {"total": 1, "channel": "UC_dead", "cause": "http_404", "read": 0},
+        )
 
     def test_a_read_only_database_is_a_total_outage_too(self, monkeypatch):
         # Every feed reads fine, nothing can be stored: just as un-polled, just as red.

frontend/src/components/Scheduler.tsx

@@ -35,7 +35,7 @@ import { useContextMenu } from "./ui/useContextMenu";
 import { ContextMenu } from "./ui/ContextMenu";
 import { MoreButton } from "./ui/MoreButton";
 import { type ActionMenuItem } from "./ui/ActionMenu";
-import { jobResultText } from "../lib/jobResult";
+import { jobFailureText, jobResultText } from "../lib/jobResult";
 
 const POLL_MS = 4000;
 // While any job is running, poll faster so short scheduled runs aren't missed between ticks.
@@ -257,7 +257,10 @@ function JobRow({
               ? t("scheduler.lastRun", { time: relativeTime(job.last_finished, lang) })
               : t("scheduler.neverRun")}
           {job.last_error ? (
-            <span className="text-danger"> · {job.last_error}</span>
+            <span className="text-danger">
+              {" · "}
+              {jobFailureText(t, job.result, lang) ?? job.last_error}
+            </span>
           ) : job.result ? (
             <span> · {jobResultText(t, job.result, lang)}</span>
           ) : job.last_result ? (

frontend/src/i18n/locales/en/scheduler.json

@@ -186,5 +186,14 @@
     "lowquota": "low quota",
     "noreadscope": "no YouTube read access",
     "busy": "another sync is running"
+  },
+  "failure": {
+    "rss_all_failed": "The RSS feed answered for none of the {{total}} channels — the first: {{channel}}, {{cause}}. Read through the API instead: {{read}}"
+  },
+  "rssCause": {
+    "http": "HTTP {{status}}",
+    "transport": "unreachable",
+    "apply": "could not be saved",
+    "error": "unexpected error"
   }
 }

frontend/src/i18n/locales/hu/scheduler.json

@@ -186,5 +186,14 @@
     "lowquota": "kevés a kvóta",
     "noreadscope": "nincs YouTube-olvasási jogosultság",
     "busy": "egy másik szinkron fut"
+  },
+  "failure": {
+    "rss_all_failed": "Az RSS-hírcsatorna egyik csatornánál sem válaszolt ({{total}}) — az első: {{channel}}, {{cause}}. Az API-n át beolvasva helyette: {{read}}"
+  },
+  "rssCause": {
+    "http": "HTTP {{status}}",
+    "transport": "nem érhető el",
+    "apply": "nem sikerült menteni",
+    "error": "váratlan hiba"
   }
 }

frontend/src/lib/jobResult.dom.test.ts

@@ -4,7 +4,7 @@
 // one-liner was "recent={'channels_processed': 0, …}, deep={…}" — English keys and a Python repr.
 import { afterEach, describe, expect, it } from "vitest";
 import i18n, { setLanguage } from "../i18n";
-import { jobResultText, parseSummary } from "./jobResult";
+import { jobFailureText, jobResultText, jobRunText, parseSummary } from "./jobResult";
 
 afterEach(() => setLanguage("en"));
 
@@ -65,3 +65,34 @@ describe("an older notice's one-liner", () => {
     expect(parseSummary(null)).toBeNull();
   });
 });
+
+// E31: the audit log showed a failed RSS poll as the server's English sentence ("RSS poll failed for
+// all 399 channels — first: …") under a Hungarian UI. A failure the job names rides along as data.
+describe("a failed run", () => {
+  const run = {
+    job_id: "rss_poll",
+    status: "error",
+    summary:
+      "RSS poll failed for all 399 channels — first: UCx: RSS fetch for UCx returned HTTP 404",
+    result: { failure: "rss_all_failed", total: 1399, channel: "UCx", cause: "http_404", read: 0 },
+  };
+
+  it("says the failure the job named in the reader's language", () => {
+    const t = i18n.getFixedT("hu");
+    expect(jobRunText(t, run, "hu").body).toBe(
+      "Az RSS-hírcsatorna egyik csatornánál sem válaszolt (1399) — az első: UCx, HTTP 404. " +
+        "Az API-n át beolvasva helyette: 0",
+    );
+    expect(jobFailureText(t, { ...run.result, cause: "transport" }, "hu")).toContain(
+      "UCx, nem érhető el.",
+    );
+  });
+
+  it("keeps any other failure's own text", () => {
+    const t = i18n.getFixedT("hu");
+    expect(jobRunText(t, { ...run, summary: "Plex returned 500", result: null }, "hu").body).toBe(
+      "Plex returned 500",
+    );
+    expect(jobFailureText(t, { failure: "moon_is_full" }, "hu")).toBeNull();
+  });
+});

frontend/src/lib/jobResult.ts

@@ -38,10 +38,30 @@ export function jobResultText(t: TFunction, result: JobResult, lang: string): st
     .join(" · ");
 }
 
+/** A failure the job named (the server's `progress.JobFailed`: `{failure: <reason>, …params}`) in the
+ *  reader's language (E31); null for any other failure, which keeps the upstream's own text. */
+export function jobFailureText(t: TFunction, result: unknown, lang: string): string | null {
+  if (!result || typeof result !== "object") return null;
+  const { failure, ...params } = result as Record<string, unknown>;
+  if (typeof failure !== "string") return null;
+  const values: Record<string, string> = {};
+  for (const [k, v] of Object.entries(params))
+    values[k] = typeof v === "number" ? formatNumber(v, lang) : String(v);
+  if (typeof params.cause === "string") values.cause = rssCause(t, params.cause);
+  return t(`scheduler.failure.${failure}`, { ...values, defaultValue: "" }) || null;
+}
+
+/** Why a feed did not answer, from the poll's reason code (`http_404`, `transport`, …). */
+function rssCause(t: TFunction, cause: string): string {
+  const http = /^http_(\d+)$/.exec(cause);
+  if (http) return t("scheduler.rssCause.http", { status: http[1] });
+  return t(`scheduler.rssCause.${cause}`, { defaultValue: cause });
+}
+
 /** What a job run said, as the inbox notice and the audit row both show it (E30): a title naming the job
  *  and how the run ended, and its result in the reader's language — from the data when it rode along,
- *  else read back from the English one-liner. A skipped run names only why; a failed run keeps the
- *  upstream's own error text (it is diagnostic). */
+ *  else read back from the English one-liner. A skipped run names only why; a failed run says the
+ *  failure the job named (`jobFailureText`, E31), else keeps the upstream's own text (diagnostic). */
 export function jobRunText(
   t: TFunction,
   run: { job_id: string; status?: unknown; summary?: unknown; result?: unknown },
@@ -65,10 +85,12 @@ export function jobRunText(
   }
   // A skipped run's title already says "skipped": its body is only the reason, not "skipped: <reason>".
   const reason = run.status === "skipped" ? onlySkipReason(result) : null;
+  const failure = run.status === "error" ? jobFailureText(t, run.result, lang) : null;
   return {
     title: t(titleKey, { job }),
-    body:
-      reason !== null
+    body: failure
+      ? failure
+      : reason !== null
         ? t(`scheduler.skip.${vocabKey(reason)}`, { defaultValue: reason })
         : result
           ? jobResultText(t, result, lang)