feat(playwright): adopt per-thread sessions for shared Chrome automation

skills/gemini-music-web/SKILL.md

@@ -21,15 +21,14 @@ description: "Generate music in Gemini web via browser automation, download resu
 - Ensure browser session can access Gemini (`https://gemini.google.com/app`).
 - If login, captcha, or MFA is required, pause and ask user to complete it manually.
 - Use the shared Playwright session policy across all skills:
-  - `export PLAYWRIGHT_SHARED_SESSION=codex-shared`
-  - Invoke Playwright CLI through `/Users/xd/java/xhs/tools/pw` (do not pass `--session` manually).
+  - Auto session policy: `tools/pw` derives one Playwright session per `CODEX_THREAD_ID` (fallback: `PLAYWRIGHT_SESSION_OWNER` or explicit `--session`).
+  - Invoke Playwright CLI through `/Users/xd/java/xhs/tools/pw`; use `--session <name>` only when explicit multi-session isolation is needed.
 - Decide output directory before generation, for example:
   - `/Users/xd/java/xhs/output/gemini-music`
 
 Quick run:
 
 ```bash
-export PLAYWRIGHT_SHARED_SESSION=codex-shared
 python3 scripts/run_music_flow.py \
   --prompt "创作一段 90 BPM 的 lo-fi hiphop，温暖、夜晚、钢琴和刷镲，时长 30 秒。" \
   --target /Users/xd/java/xhs/output/gemini-music \
@@ -156,6 +155,6 @@ Return:
 
 ## Scripts
 
-- `/Users/xd/java/xhs/tools/pw`: Shared Playwright CLI entrypoint with fixed session + lock.
+- `/Users/xd/java/xhs/tools/pw`: Shared Playwright CLI entrypoint with per-session lock, auto per-thread session resolution, and shared Chrome CDP defaults.
 - `scripts/run_music_flow.py`: End-to-end runner (login gate, enter music tool, generate, download MP3, collect files).
 - `scripts/collect_downloads.py`: Collect recent downloaded audio files with fallback sources, dedupe, and manifest.