fix: Windows/Linux cross-platform compatibility

[nmbrthirteen]

Summary

podcli ran cleanly on macOS but had several Windows-breaking issues (a couple also affect non-UTF-8 Linux locales). This makes it work on Windows and Linux without changing macOS behavior — every edit is either platform-conditional or purely additive.

Fixes

1. Python interpreter discovery on Windows — src/config/paths.ts
detectPython() now branches on process.platform === "win32": looks for venv\Scripts\python.exe and falls back to python (not python3). This was the hard blocker — the MCP server and web UI spawn this interpreter for every backend task, so on Windows nothing could run.

2. UTF-8 encoding — 40 text-mode open() calls across 17 backend files
   Added encoding="utf-8" to every text-mode open()/json target. Windows defaults text mode to cp1252, which silently corrupts UTF-8 transcripts on read and raises UnicodeEncodeError when writing JSON containing emoji/non-Latin text. Binary opens, wave.open, urlopen, os.fdopen, and the os.devnull→subprocess fd were deliberately left untouched.

3. Thumbnail fonts — backend/services/thumbnail_generator.py
   Added C:/Windows/Fonts/arial*.ttf to the TTC face list and standalone fallbacks (mirrors the existing pattern in caption_renderer.py). Previously Windows fell back to PIL's bitmap default font.

4. Reveal-in-folder — backend/cli.py
   Added one _reveal_in_os() helper (open / os.startfile / xdg-open per platform, best-effort) and routed all 4 former call sites through it. Previously these ran xdg-open on Windows, which doesn't exist.

5. UI basename helpers — src/ui/client/lib.ts, src/ui/web-server.ts
   Split on /[/\\]/ so Windows backslash paths render the filename rather than the whole path.

6. npm/npx/.cmd shim execution on Windows — backend/cli.py, backend/services/thumbnail_html.py
   On Windows npm/npx are .cmd batch files that Python's subprocess can't run without a shell. The webui menu's npm run build/ui:prod now pass shell=True on Windows; the Playwright thumbnail fallback prefers the playwright.cmd shim and runs npx/.cmd candidates with shell=True on Windows. shell=True is Windows-only (it would break the arg list on POSIX). Node detection itself (shutil.which("node") → invoked by absolute path) was already correct.

7. Native file dialog on Windows — src/ui/web-server.ts
/api/browse-file had only osascript (mac) / zenity (Linux). Added a Windows branch using a PowerShell OpenFileDialog (base64 -EncodedCommand to avoid quoting issues, -STA for WinForms).

Verification

• vitest run: 47/47 pass
• tsc --noEmit: clean
• python3 -m compileall backend: OK
• Re-audit: no remaining unencoded text open() except the intentional os.devnull (subprocess fd, encoding irrelevant).

Not included (follow-ups)

• ffmpeg concat backslash paths (video_cut.py:77, video_processor.py:1793): writes file '<abspath>' with backslashes on Windows. ffmpeg generally accepts these, so left as-is; normalizing to / would be a safe future hardening.
• No setup.ps1 / podcli.cmd: a native Windows installer/launcher is a larger, separate piece. The MCP server still runs via node dist/index.js + npm scripts.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 7b1204a9-e829-41d4-8b11-90e55634b250

📥 Commits

Reviewing files that changed from the base of the PR and between ded1120 and a8ab102.

📒 Files selected for processing (22)

• README.md
• backend/cli.py
• backend/presets.py
• backend/services/asset_store.py
• backend/services/claude_suggest.py
• backend/services/clip_generator.py
• backend/services/clips_history.py
• backend/services/content_generator.py
• backend/services/corrections.py
• backend/services/encoder.py
• backend/services/integrations/youtube/client.py
• backend/services/integrations/youtube/learnings.py
• backend/services/thumbnail_ai.py
• backend/services/thumbnail_generator.py
• backend/services/thumbnail_html.py
• backend/services/transcript_packer.py
• backend/services/video_cut.py
• backend/services/video_processor.py
• podcli.cmd
• setup.ps1
• src/ui/client/lib.ts
• src/ui/web-server.ts

📝 Walkthrough

Walkthrough

This PR standardizes file I/O across the full stack to use explicit UTF-8 encoding, adds a cross-platform file/folder opening helper to replace platform-specific subprocess calls, and improves Windows compatibility by handling backslash path separators in TypeScript and supporting Windows Python venv and font paths.

Changes

Cross-platform file I/O and encoding

Layer / File(s)	Summary
Cross-platform file/folder opening helper and CLI integration backend/cli.py	Introduces _reveal_in_os(path: str) helper that uses platform-native commands (open on macOS, os.startfile on Windows, xdg-open elsewhere) to open files and folders, replacing four separate inline subprocess invocations during clip review, rerender preview, post-render preview, and output folder access.
UTF-8 encoding for CLI file operations backend/cli.py	Standardizes all file reads and writes in the CLI layer to use explicit UTF-8 encoding: transcript loading, thumbnail config reading, content markdown writing, knowledge-base preview/read/write operations, UI state persistence, cache transcript reads, and .env access for HF_TOKEN and environment setup.
UTF-8 encoding standardization across backend services backend/presets.py, backend/services/{asset_store,clip_generator,clips_history,content_generator,corrections,encoder,claude_suggest,transcript_packer,thumbnail_ai,thumbnail_html,video_cut,video_processor}.py, backend/services/integrations/youtube/{client,learnings}.py	Updates preset persistence, asset registry, clip generation, clips history, content generation, corrections, encoder cache, Claude suggestion, transcript packing, thumbnail configuration, video processing, and YouTube integration modules to open all JSON and markdown files with explicit encoding="utf-8" for deterministic behavior across platforms.
Windows platform support: venv paths, path parsing, and font resolution src/config/paths.ts, src/ui/client/lib.ts, src/ui/web-server.ts, backend/services/thumbnail_generator.py	Adds platform-aware Python venv detection (Windows: venv/Scripts/python.exe, others: venv/bin/python3), updates TypeScript path utilities and prompt generation to split on both / and \ separators, adds UTF-8 encoding for thumbnail config reads, and extends font-file resolution in thumbnail generation to include Windows system fonts (C:/Windows/Fonts/{arial,arialbd}.ttf, .ttc files).

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

Possibly related PRs

• nmbrthirteen/podcli#5: Both PRs update backend/services/clips_history.py's load_clips_history() and save_clips_history() functions (this PR adds UTF-8 encoding, while PR #5 extends clips-history deletion and persistence behavior).

Poem

🐰 Encoding all the files in UTF today,
Cross-platform paths now leading the way,
Windows fonts and venvs, a bunny's delight,
From bash to backslash, everything's right! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'fix: Windows/Linux cross-platform compatibility' accurately summarizes the main objective of the PR, which is to fix cross-platform compatibility issues between Windows and Linux while preserving macOS behavior.
Docstring Coverage	✅ Passed	Docstring coverage is 85.37% which is sufficient. The required threshold is 80.00%.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/windows-linux-compat

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@backend/cli.py`:
- Around line 56-57: The except Exception: pass is silently swallowing
reveal/open failures; replace it with an except Exception as e that emits a
minimal warning to stderr (e.g., sys.stderr.write or logging.warning) including
a short context like "Failed to reveal/open path:" and the exception message so
users get feedback when the desktop integration or opener fails; update the
block where the code currently uses "except Exception: pass" (the reveal/open
error handler) to log the error instead of suppressing it.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: e399e53d-0d39-47bc-a1f0-c6fbc6f7c74c

📥 Commits

Reviewing files that changed from the base of the PR and between 3cb1875 and ded1120.

📒 Files selected for processing (20)

• backend/cli.py
• backend/presets.py
• backend/services/asset_store.py
• backend/services/claude_suggest.py
• backend/services/clip_generator.py
• backend/services/clips_history.py
• backend/services/content_generator.py
• backend/services/corrections.py
• backend/services/encoder.py
• backend/services/integrations/youtube/client.py
• backend/services/integrations/youtube/learnings.py
• backend/services/thumbnail_ai.py
• backend/services/thumbnail_generator.py
• backend/services/thumbnail_html.py
• backend/services/transcript_packer.py
• backend/services/video_cut.py
• backend/services/video_processor.py
• src/config/paths.ts
• src/ui/client/lib.ts
• src/ui/web-server.ts