playground: CRDT engine to snapshot format 8 (collab v0.37, crdt v0.39)

[tannevaled]

Live collaboration was pinned to go-crdt/collab v0.33.0 / crdt v0.35.0 while the CRDT engine moved on. This takes the playground to collab v0.37.0 + crdt v0.39.0 — the pair that writes snapshot format version 8 (~45% smaller snapshots), and folds in the federation / eviction / read-only-participant-retention fixes from collab v0.34–v0.37.

Why the latest pair, not Renovate #115

Renovate #115 bumps to collab v0.36.1 / crdt v0.37.0 — which is before snapshot v8 (introduced in crdt v0.38.0, required by collab v0.37.0). To actually ship the smaller-snapshot win, the playground needs this pair. #115 remains for its richdoc/toolkit bumps.

Format-8 compatibility

The upgrade note warns a v0.39 server sends format 8 to joining clients and no crdt before v0.38 can read it — that is a cross-version server concern. Here both peers run the same deployed wasm build, so host and guest are always on the same format; there is no mixed-version path. Serverless signalling (paste blob / QR) and the in-memory-only token posture are unchanged.

Verification

Local: GOOS=js GOARCH=wasm go build ./..., go vet, gofmt -l, and the native collab sync suite (collab_test, collab_twotab_test, collab_localtab*, collab_panel_flow, collab_peer_identity, collab_qr, collab_paste_field) all pass on the new pair. The headless two-tab browser-proofs run in CI. Diff is playground/go.mod + go.sum only.

🤖 Generated with Claude Code

[tannevaled]

Held as draft — this bump needs a cross-org change first.

CI's two-tab browser-proofs fail on the new pair:

• TestCollabLocalTabConvergence: tabs connect (same-browser BroadcastChannel) but never converge — B never sees A's edit, no remote carets, buffers don't merge.
• TestCollabLocalTabSequentialConvergence: the peers time out before reaching connected (peers:0).

Root cause: the live-sync seam is inside toolkit.CollabText (go-widgets/toolkit), whose collabtext.go consumes client.Changes() + client.TakeChanges(). toolkit v0.294.0 pins go-crdt/collab v0.33.0. Bumping the playground to collab v0.37 makes Go MVS run toolkit's CollabText against v0.37 — a version it was never written or tested against — and the v0.34–v0.37 change-notification / version-vector / collection changes break its consumption. The wasm build passes (signatures are unchanged); the break is purely semantic, which is why only the browser-proofs catch it.

Blocker: go-widgets/toolkit's CollabText must be updated to collab v0.37 (snapshot format 8) and released, then the playground bumps collab, crdt and toolkit together. Holding here on the working v0.33/v0.35 pair until then — live collaboration on main is unaffected.

[tannevaled]

Correction — this was a CI flake, not a real regression. Ready to merge.

I re-ran the browser proofs locally (system Chrome + puppeteer-core) against exactly this pair: TestCollabLocalTabConvergence passes 4/4 and TestCollabLocalTabSequentialConvergence passes all three gaps (300/900/1200ms) — B converges on A's edit, remote carets paint, buffers merge, both directions. A native two-client-over-Pipe reproduction on collab v0.37 + crdt v0.39 also converges.

Re-running the failed CI job then went fully green (build, bricolint, test, browser-proofs). The first run hit a transient flake in the headless two-tab proofs (both collab tests at once). The earlier note about toolkit.CollabText needing a collab-v0.37 update was mistaken: MVS does run toolkit v0.294.0's CollabText against v0.37, and it converges correctly — no toolkit change is required.

Undrafting and merging.