cline: hook emission shape is wrong — JSON files vs filename-dispatch scripts

[scottmeyer]

Status: Real bug surfaced during v0.9.0 spec research and confirmed by the spec reviewer.

Affected versions: v0.8.0, v0.8.1, v0.8.2 (every release with cline hooks)

Context

v0.8.0's cline plugin emits hook configuration as .clinerules/hooks/<event>.json files (one JSON config file per event). But Cline's actual hook dispatch model is filename-based: it expects scripts named exactly by event in .clinerules/hooks/<EventName> (no extension, no JSON layer). Single handler per event, no native matcher.

The JSON files we currently emit are never fired by Cline. Scoped Cline hooks have been silently no-op since v0.8.0.

What to implement

1. In plugins/cline.go, rewrite the hook emission path:
   • Stop emitting .clinerules/hooks/<event>.json
   • Instead emit executable scripts at .clinerules/hooks/<EventName> (filename = canonical event name mapped via mapClineEvent, no extension)
   • For scoped hooks, the script content embeds the existing scope-guard wrapper inline (since Cline has no matcher layer, gating happens in the script itself)
   • For multiple hooks targeting the same event with different matchers, generate one composite script that branches on the matcher
2. Importer: update internal/importer/cline.go to read .clinerules/hooks/<EventName> (filename-as-event) instead of looking for .json files
3. Round-trip tests in internal/engine/roundtrip_test.go need updating to match
4. CHANGELOG note: the JSON files emitted by v0.8.0-v0.8.2 are orphans on disk and can be safely deleted

v0.9.0 includes this fix

The v0.9.0 design pass mandates filename-dispatch (see SPEC.md §4.4.5). This issue tracks the v0.8.3 backport for users not yet on v0.9.

Acceptance criteria

• .clinerules/hooks/PreToolUse (executable, no extension) is emitted instead of PreToolUse.json
• Round-trip test confirms the new shape
• A real Cline install actually fires the hook (manual smoke test)
• CHANGELOG documents the orphan-JSON cleanup