Add project roadmap

Prioritized A/B/C plan: safety net (tests, subprocess hardening, error
surfacing) first, then finishing fork features, then modernization.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

ROADMAP.md

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+# Roadmap — devedeng-extended
+
+Direction for the hardsub/auto-split fork of DeVeDe-NG. Ordered by leverage:
+the safety net comes first because everything after it is safer to build once
+it exists. Checkboxes track status.
+
+## Phase A — Safety net & correctness (do first)
+
+- [ ] **A1. Automated test suite (pytest).** The project has no tests today;
+      every change is hand-verified. Start with the pure logic that already
+      isolates cleanly:
+      - `plan_disc_split`, `_movie_chapter_seconds`, `_nearest_chapter_before`
+      - `compute_high_profile_bitrate`
+      - ffmpeg/avconv command generation (`convert_file` → `command_var`) with
+        mock `file_project` objects, asserting flags for each profile,
+        text/image hardsub, 2-pass, even pad/crop, AC3 448k.
+      Add a `tests/` dir and a CI workflow (Codeberg Actions/Woodpecker). This
+      would have caught the 448k→384k clamp bug automatically.
+
+- [ ] **A2. Harden subprocess I/O (kills the deadlock class).** `executor`
+      reads child stdout/stderr via blocking `GLib.IOChannel` watches; a stalled
+      consumer can backpressure-deadlock the child (this bit us — ffmpeg froze
+      on a full progress pipe when the GUI wedged). The progress-file fix only
+      covers ffmpeg progress; dvdauthor/spumux/mkisofs stdout/stderr still use
+      the fragile pattern. Build one hardened helper (non-blocking reads,
+      drain-on-close, bounded buffers, never let a child block on a pipe we own)
+      and route every backend through it.
+
+- [ ] **A3. Surface real errors to the user.** Failures show a generic error
+      window; the actual failing command + stderr is buried in the log. On
+      failure, show the command and the last N stderr lines. (Diagnosing the
+      deadlock this session required strace/`/proc` spelunking.)
+
+- [ ] **A4. Narrow bare `except:` blocks.** Config loading, `pre_function`/
+      `post_function`, ffprobe JSON parsing, etc. use `except: pass`, silently
+      swallowing real bugs. Catch specific exceptions; log the rest.
+
+## Phase B — Finish & polish current fork features
+
+- [ ] **B1. Multi-disc burning flow.** The split feature makes N ISOs but the
+      done-handler only offers the last one. Add "burn disc 1 → prompt to insert
+      disc 2 → …" so the split workflow is complete end to end.
+
+- [ ] **B2. Per-disc menu space in the split planner.** `plan_disc_split`
+      reserves menu space only on disc 0, but per-disc menus now exist on every
+      split disc. Menus are small (a few MB) and fit in the 10% margin, so this
+      is a correctness nicety, not urgent. Reserve menu bytes per disc.
+
+- [ ] **B3. OCR for image subtitles (optional path).** Image subs (PGS/VOBSUB)
+      are currently overlaid as bitmaps. Add an optional tesseract/OCR path to
+      convert them to styled text when the user prefers crisp text and the tool
+      is installed (this was the originally-discussed "OCR optional" branch).
+
+- [ ] **B4. Progress UX.** One raw-percentage bar per core, no overall view.
+      Add: ETA per encode, an overall "disc N of M / file X of Y" indicator, and
+      persistent per-file labels. Matters most for long unattended batches.
+
+- [ ] **B5. "Already DVD" guard.** Warn when the input is already 720×480
+      MPEG-2 (likely a previous DVD output) to avoid a needless second-
+      generation transcode.
+
+## Phase C — Modernization & reach
+
+- [ ] **C1. Drop the avconv/avprobe backend.** libav/avconv has been defunct
+      since ~2018 and doubles the maintenance surface for every encode change
+      (each ffmpeg edit must be mirrored). Remove it once ffmpeg is the assumed
+      backend; simplifies `converter.py` and the converters.
+
+- [ ] **C2. CLI / headless mode.** Everything requires the GTK GUI. A
+      `devede-ng --project x.devedeng --output dir/` (and ideally a
+      direct `input video → hardsub → 480p NTSC → split → ISOs` one-shot) would
+      enable scripting, server use, and far easier automated testing.
+
+- [ ] **C3. GTK3 → GTK4.** GTK3 is maintenance-only; this is the long-term
+      wall. Large effort; schedule deliberately.
+
+- [ ] **C4. Consolidate UI construction.** GLADE `.ui` files are hand-edited
+      XML (fragile — newer widgets are built in Python instead). Pick one
+      approach (likely programmatic or GTK4 templates) and converge.
+
+## Known limitations carried from current work
+- Split discs: burning is manual per-disc (see B1).
+- High profile uses a 3000k quality floor / 9000k cap; near-cap bitrates stress
+  old players (acceptable — it's the explicit "high quality" choice).
+- No tests / no CI yet (A1).