Collapse whitespace left by stripped filename separators

A real feed titled with pipe separators produced a folder named
"Get in the Trunk  Anthology Series  Delta Green": removing a forbidden
character left the gap around it. Runs of whitespace now collapse, and
control characters map to a space rather than vanishing.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01RPyeapneuXrCdojsaiXGbe

PROGRESS.md

@@ -30,6 +30,33 @@ The full design and step list live in the plan file at
 
 ---
 
+## 2026-09-10 — Tested against a real feed (Patreon / Glass Cannon)
+
+First run against a live subscriber feed: 131 items, 6.17 GB total, all `audio/mpeg`, no `<ttl>`.
+Parsed clean, titled `Get in the Trunk | Anthology Series | Delta Green`, downloaded a valid MP3
+(`file` confirms ID3v2.3, MPEG layer III). A second scan pulled the *next* episode, confirming
+`max_new_per_check` defers rather than drops. Over the socket: 101 progress events for a 79 MB
+episode -- whole-percent throttling behaving exactly as intended -- then `download_done`,
+`feed_done`, `scan_done`.
+
+**Fixed: stripped separators left doubled spaces.** The feed title separates words with `|`, a
+forbidden filename character, so the folder came out `Get in the Trunk  Anthology Series  Delta
+Green`. `sanitize()` now collapses runs of whitespace (and maps control characters to a space
+rather than deleting them). The Python had the same wart.
+
+**Worth knowing, not a bug:**
+
+- The channel-level `itunes:explicit` is `true`, so with the default `allow_explicit = false` all
+  131 episodes are skipped. Because filter verdicts are recorded once at discovery, flipping the
+  setting afterwards does not re-evaluate enclosures already marked `skipped` -- they would need a
+  `UPDATE enclosures SET state='pending'`. Worth a `ipx retry <feed>` command if this bites.
+- Patreon sends neither `etag` nor `last-modified` on a GET (a `last-modified` does appear on HEAD,
+  which is what made it look briefly like a storage bug). So this feed can never 304: every poll
+  re-fetches ~160 KB and re-parses 131 entries, and `interval_mins` is the only thing limiting the
+  rate. Cheap, but it means conditional GET buys nothing here.
+
+---
+
 ## 2026-09-09 — Step 8: OPML and polish
 
 `ipx add <url>` fetches the feed to name it from its own title (`Accidental Tech Podcast` ->