session 2026-06-12: Studium Engine Stage-1 planning charter + Fable[1m] routing decision; ARC running-head mobile-Safari gap parked (opt i); skill-harvest proposals

claude/memory/skill-harvest-register.md

@@ -125,3 +125,12 @@ The single place proposed skills live so they don't evaporate between sessions.
 | **`/measure-render` (headless-Chrome box-model/scroll harness)** | create skill OR ladder note | **RE-REINFORCED (4th day of evidence).** Proposed 2026-06-09 (compass fix) + reinforced 06-09 pm; today drove the ENTIRE §VII.f build — reveal opacity across scroll, body-column-axis alignment (598/798 constant), the dissolve-below-rule geometry, the frontispiece no-scroll proof, the compass graded reveal. The build would not have been groundable without it. Earns its own skill. | `/measure-render` skill OR verification-ladder | **PROPOSED (strongly reinforced, 4th instance)** |
 
 *Watch-list (not yet a skill proposal): the **open-work register pattern** — when tracking surfaces drift, consolidate them into ONE code-verified source of truth (built `project-arc-open-work-register.md` today). Overlaps `/spec-code-audit` for the spec↔code half; the new part is the content/governance/Phase-2 reconciliation. May graduate to a `/reconcile-open-work` discipline if it recurs on another workstream (L1/be).*
+
+## New proposals (2026-06-12 — Studium planning charter / model-routing day, awaiting steward)
+
+| Element | Kind | One-line | Where it lands | Status |
+|---------|------|----------|----------------|--------|
+| **`/model-handoff` (premium-model scope charter)** | create skill OR reference card | When switching to an expensive/premium model (Fable 5 = 2× Opus rate; burn scales with context×session-length) for a **bounded high-leverage phase**, first write the **scope charter on the cheap model** — the bounding/orientation reasoning is cheap, the content reasoning is where the premium pays. Charter shape (proven today, `studium-engine/docs/stage-1-planning-brief-2026-06-12.md`): §0 operating discipline (1M window — `claude-fable-5[1m]` not bare-200k; reset thinking level on switch; no sprawl) · §1 settled decisions (don't re-derive) · §2 already-read summaries (don't re-read) · §3 bounded reading list (verified paths; out-of-scope named) · §4 exact deliverables · §5 report-and-stop. Plus: **clear+wake rather than switch-in-place** so the premium model never rereads the long chat; **artifacts (not chat) are the handoff** (the Reddit "knowledge in files not chat" insight, but **reject** its "query the graph instead of files" — that's the index-as-source-of-truth shape). Recurs every Fable session in the 06-22 window and beyond. | a `/model-handoff` skill OR a reference card beside the verification ladder | **PROPOSED** |
+| **verification-ladder: feature-detect gates can lie** | verification-ladder entry | A CSS `@supports(feature)` (or any capability probe) can return **true on a platform where the feature is non-functional** — today the ARC §VII.f running head: `@supports(animation-timeline:view())` is `true` on iOS Safari 26, but mobile WebKit won't *drive* the scroll-reveal on a `position:fixed`+`timeline-scope` consumer (`display:block, opacity:0`); desktop Safari works. So a progressive-enhancement "no-support shows nothing" contract can be **silently false** on a major platform. Antidote: **verify the feature on the real engine/device, not the support table** — `CSS.supports(...)` + computed-`opacity`/`getBoundingClientRect` on-device (the iOS analog of the headless-Chrome box-model harness). Kin to `/measure-render`; one level up (feature-functionality, not box-model). | `reference-verification-ladder.md` | **PROPOSED** |
+
+*(Both genuine, both recurring-shaped — not manufactured. The first will pay off the very next time the steward opens a Fable window; the second generalizes today's running-head correction into a standing instrument.)*