feat(subscriptions): live posts-processed progress on backfill/recovery — #704 step 2

The running badge only showed the chunk counter; now it shows posts walked
— real walk progress. The ingester already reports posts_processed per
chunk (step 1); the backfill lifecycle accumulates it into
config_overrides._backfill_posts across chunks. SourceRecord exposes
backfill_posts; start_backfill/start_recovery clear it (fresh walk); stop
clears it too. SourceRow/SourceCard badge renders "Recovering · 45 posts"
(falls back to "(N)" chunks before any posts are counted).

Per-chunk accumulation (no mid-walk DB write) — simple and race-free; a
small over-count from each chunk re-walking its resumed page is fine for a
progress indicator.

Tests: lifecycle accumulates posts_processed across chunks; start clears a
prior _backfill_posts and the record exposes it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/app/services/download_service.py

@@ -515,6 +515,13 @@ class DownloadService:
         new_overrides = dict(src.config_overrides or {})
         chunks = int(new_overrides.get("_backfill_chunks", 0)) + 1
         new_overrides["_backfill_chunks"] = chunks
+        # plan #704 (#5): accumulate posts-processed across chunks so the badge
+        # shows live walk progress, not just the chunk count. Cleared on
+        # (re)start. (Slight over-count: each chunk re-walks the resumed page —
+        # fine for a progress indicator.)
+        new_overrides["_backfill_posts"] = int(
+            new_overrides.get("_backfill_posts", 0)
+        ) + int(getattr(dl_result, "posts_processed", 0) or 0)
 
         completed = (
             dl_result.success

backend/app/services/source_service.py

@@ -70,6 +70,9 @@ class SourceRecord:
     # plan #697: a running deep-walk that bypasses the Patreon seen-ledger
     # (recovery) vs. a normal backfill. Lets the badge label it "Recovering".
     backfill_bypass_seen: bool
+    # plan #704: cumulative posts processed across the walk's chunks — live
+    # progress for the badge.
+    backfill_posts: int
 
     def to_dict(self) -> dict:
         return {
@@ -91,6 +94,7 @@ class SourceRecord:
             "backfill_state": self.backfill_state,
             "backfill_chunks": self.backfill_chunks,
             "backfill_bypass_seen": self.backfill_bypass_seen,
+            "backfill_posts": self.backfill_posts,
         }
 
 
@@ -167,6 +171,7 @@ class SourceService:
             backfill_state=co.get("_backfill_state"),
             backfill_chunks=int(co.get("_backfill_chunks", 0)),
             backfill_bypass_seen=bool(co.get("_backfill_bypass_seen")),
+            backfill_posts=int(co.get("_backfill_posts", 0)),
         )
 
     async def _row_to_record(self, source: Source) -> SourceRecord:
@@ -317,7 +322,8 @@ class SourceService:
             raise LookupError(f"source id={source_id} not found")
         co = dict(source.config_overrides or {})
         co["_backfill_state"] = "running"
-        for k in ("_backfill_cursor", "_backfill_cursor_stalls", "_backfill_chunks"):
+        for k in ("_backfill_cursor", "_backfill_cursor_stalls", "_backfill_chunks",
+                  "_backfill_posts"):
             co.pop(k, None)
         source.config_overrides = co
         source.backfill_runs_remaining = BACKFILL_MAX_CHUNKS
@@ -345,7 +351,8 @@ class SourceService:
         co = dict(source.config_overrides or {})
         co["_backfill_state"] = "running"
         co["_backfill_bypass_seen"] = True
-        for k in ("_backfill_cursor", "_backfill_cursor_stalls", "_backfill_chunks"):
+        for k in ("_backfill_cursor", "_backfill_cursor_stalls", "_backfill_chunks",
+                  "_backfill_posts"):
             co.pop(k, None)
         source.config_overrides = co
         source.backfill_runs_remaining = BACKFILL_MAX_CHUNKS
@@ -362,7 +369,7 @@ class SourceService:
             raise LookupError(f"source id={source_id} not found")
         co = dict(source.config_overrides or {})
         for k in ("_backfill_state", "_backfill_cursor", "_backfill_cursor_stalls",
-                  "_backfill_chunks", "_backfill_bypass_seen"):
+                  "_backfill_chunks", "_backfill_bypass_seen", "_backfill_posts"):
             co.pop(k, None)
         source.config_overrides = co
         source.backfill_runs_remaining = 0