feat(scene): auto-detect + scenes.yaml persistence (P2)

[chenchaoyi]

Summary

P1 (#114) shipped scene awareness but kept resolution opt-in — scenes fired only via --scene or DITING_SCENE, defaulting to home otherwise. Real-world feedback the moment P1 merged: "I'm clearly in an office (many same-name APs, enterprise auth), why does diting still show [家]?" That's the P1 contract working as designed, but not the experience the user wants.

P2 closes the gap. Default behaviour flips from "always home unless told otherwise" → "diting figures it out."

Two pieces working together

1. scenes.yaml per-network persistence

Same idea as aps.yaml: optional file in cwd (DITING_SCENES_FILE overrides path), git-ignored, human-curated only. Diting NEVER writes back. Maps SSID → scene, with gateway_mac as fallback for SSID-collision cases (eduroam everywhere, multiple homes with the same SSID).

networks:
  - ssid: HomeNet
    scene: home
  - ssid: Meituan
    scene: office
  - gateway_mac: 14:51:7e:71:5a:1a
    scene: office

2. Auto-detect heuristic

When no CLI / env / yaml decides, diting inspects the active Wi-Fi connection synchronously at startup. Pure-function classifier, no probes, no phone-home:

Rule	Condition	→ Scene
1	security contains "Enterprise" (case-insensitive)	office
2	visible_bssid_count >= 30 (CoreWLAN scan cache)	office
3	otherwise	home

public stays opt-in (captive-portal detection without active probing is unreliable).

Resolution precedence (5-tier, was 3)

1. --scene SCENE                       (cli)
2. DITING_SCENE env var                (env)
3. scenes.yaml SSID/gateway_mac match  (yaml)   ← new
4. Auto-detect heuristic               (auto)   ← new
5. Default home                        (default)

scene_source JSONL field extends from {cli, env, default} to {cli, env, yaml, auto, default} — session_meta records exactly which tier resolved. Analyzer + LLM bundle pick up new sources automatically (the existing scene_summary handles arbitrary source strings).

Banner

When source is yaml or auto, one line to stderr explains the choice:

auto-detected scene: office (WPA2 Enterprise auth)
pinned scene: office (matched "Meituan" in scenes.yaml)

CLI / env are silent (user knows what they asked for). DITING_SCENE_QUIET=1 silences for scripts.

What's in this PR

• openspec/changes/add-scene-autodetect-and-persistence/ — proposal / design / tasks + 3 spec deltas (scenes / event-log / tui-shell)
• src/diting/scenes_config.py (new) — SceneAssignment, SceneRegistry, load_scenes_registry, lookup helpers
• src/diting/scene.py — SOURCE_YAML / SOURCE_AUTO constants, classify_environment heuristic
• src/diting/cli.py — _resolve_scene_at_startup (5-tier resolver), _gateway_mac_for_router_ip (ARP lookup), _emit_scene_banner
• src/diting/i18n.py — EN + ZH banner strings
• scenes.example.yaml (new, repo root)
• .gitignore — adds scenes.yaml
• tests/test_scenes_config.py (new) — 12 tests
• tests/test_scene.py — 10 new heuristic tests
• tests/test_cli.py — 8 new startup + banner tests
• README.md + docs/zh/README.md — extended ## Scenes with auto-detect / yaml subsections
• CHANGELOG.md + docs/zh/CHANGELOG.md — ## [Unreleased] → ### Added
• tests/TESTING.md + docs/zh/TESTING.md — 3 new rows under scenes

Test plan

• uv run pytest — 856 passed (was 826 in P1; +30 new)
• uv run python scripts/tui_snapshot.py --mode regression — green
• openspec validate --specs --strict — 22/22 passed
• openspec validate add-scene-autodetect-and-persistence --strict — valid
• Real-environment smoke: launch diting on Meituan corp Wi-Fi without flags, confirm banner reads auto-detected scene: office (WPA2 Enterprise auth) and chip shows [公司] / [office]
• Repeat with scenes.yaml pinning Meituan → office, confirm banner switches to pinned scene: office (matched "Meituan" in scenes.yaml)

What this PR does NOT do

• Public auto-detection. Open Wi-Fi exists in homes, offices, and public spaces; can't distinguish without active probing. Still --scene public.
• Mid-session reclassification. Scene fixed at startup. Roaming home → office mid-session keeps the original scene until next launch.
• Other scene-aware knobs (roam_alert, bonjour_categories, lan_inventory, event_throttle). Still P3.
• diting writing back to scenes.yaml. Human-curated only.

Generated with Claude Code