Merge pull request 'LANGUAGE.md pilot: hand-written vocabulary + caveman rubric (Phase 1)' (#19) from language-md-pilot into main

CLAUDE.md

@@ -12,6 +12,7 @@ docs it indexes.
 3. `DECISIONS.md` — the ADRs. Decisions are settled here; do not re-litigate without a new ADR.
 4. `docs/architecture/architecture.md`, `docs/data-model.md`, `docs/use-cases/*.feature`.
 5. `docs/homelab-integration.md` — the concrete endpoints/conventions you'll need.
+6. `LANGUAGE.md` — the project vocabulary. Apply the caveman rubric before destructive operations.
 
 ## How to work in this repo
 

LANGUAGE.md

@@ -0,0 +1,26 @@
+# Vocabulary (hand-written pilot 2026-06 — will be generated by langgen in Phase 2)
+
+| Term | Means | Never say |
+|---|---|---|
+| transcript | Captions-first text of a video; the source for summarizing. Shared store keyed by `(provider, video_id)`. | "subtitles file", "the audio" |
+| video | Per-user record of a seen video; the unit of work. Not globally deduped. | "the shared video" |
+| subscription | A watched channel on a user's connection that Tapir polls for new videos. | "feed", "follow" |
+| summary | A video's produced output: summary text + highlights + takeaways + AI provenance. | "transcript" |
+| highlight | A notable point pulled from a video (`Summary.Highlights`). | "takeaway" |
+| takeaway | An actionable conclusion from a video (`Summary.Takeaways`). | "highlight" |
+| sink | A delivery destination for a summary (`store`, `brain`). New one = new adapter. | "the database" |
+| AI router | Local-first chain: local Primary → local fallback → external worst-case. | "the API" |
+| BYO-AI fallback | User's own external AI key, used only when local fails; opt-in. Without it, content is never sent externally. | "the default AI" |
+| brain | Persistent homelab knowledge store; in Tapir, one optional HTTP sink (`brain_ingest`), not the filesystem package. | "the database", "the store" |
+| LiteLLM gateway | Local AI gateway (`koala:30401/v1`); the Primary in the AI router. | "piguard", "the cloud" |
+| connection | A connected video account a user authorizes via OAuth; subscriptions hang off it. | "login", "session" |
+
+## Caveman rubric
+Before any HIGH/CRITICAL operation, output one line:
+`caveman: me <verb> <object>, not <excluded thing>`
+Valid iff: (1) only vocabulary terms + plain verbs, (2) a stranger could identify
+the exact operation, (3) names one thing explicitly NOT being done.
+
+Examples:
+- `caveman: me delete user connection, not the shared transcript`
+- `caveman: me send transcript to BYO-AI fallback, not the LiteLLM gateway`