feat(ui): action-sentence layer for extrinsic/event headlines

[JSONbored]

Closes #8371 — client-side UI deliverable. Scope note posted on the issue before implementation: the schema/API summary contract field is deferred to a follow-up rather than bundled into this PR (see the issue comment for the full reasoning).

What this does

New apps/ui/src/lib/metagraphed/chain-summaries.ts: summarizeCall()/summarizeEvent() render a one-line action sentence over the existing decode infrastructure (#4319 nested-call decode, #8322 decoded events) — the issue's own worked example, "Validator 5GQi…sQQ committed time-locked weights for SN89, revealing at round 30,777,610", instead of SubtensorModule.commit_timelocked_mechanism_weights plus a raw arg table. A pallet.method with no template returns null; callers keep today's raw rendering — a sentence is never guessed.

Grounded in real data, not assumption

• Pulled the top-40 call/event combinations by real observed volume from GET /api/v1/chain/calls?group_by=module_function and GET /api/v1/chain-events/stats — the top 20 calls alone cover ~97% of volume, so every template targets something that actually matters.
• Every template was checked against a real decoded payload fetched live from api.metagraph.sh before being written, not guessed.
• Found and worked around a real arg-shape surprise along the way: chain_events payloads are frequently positional arrays with no field names at all — confirmed live for WeightsSet ([[89], 122]), StakeAdded/StakeRemoved ([coldkey, hotkey, [amount], [amount2], [netuid], version]), NeuronRegistered ([[netuid], uid, hotkey]), and both TimelockedWeights* events — distinct from account_events's keyed-object shape, and the field order differs per event. My first coverage run (94.68%, just under the 95% bar) caught this directly: templates that assumed named fields were silently returning null on these five high-volume events. Fixed by reading positional args by index against the real captured shape for each.
• Also found RootClaimed carries no netuid field at all (just {coldkey}), and AutoStakeAdded's amount field is named incentive, not amount — both fixed to match reality rather than the assumed shape.

Wired into three surfaces

• Extrinsic detail masthead: sentence as the headline; raw module.function demotes to the existing "Call" field row further down (unchanged).
• Raw all-events feed (ChainEventCard + the desktop table in chain-events-feed.tsx): leads with the sentence, falling back to Pallet.Method when there's no template. This is shared by /events, the embedded Chain-hub preview, and anywhere else the component is reused.
• Account detail's "Signed extrinsics" section: same sentence, with the account itself as the signer context (it's filtered to extrinsics that account signed).

Coverage: 98.37%, past the 95% bar

chain-summaries.coverage.test.ts — opt-in (RUN_COVERAGE=1 npx vitest run src/lib/metagraphed/chain-summaries.coverage.test.ts), describe.skipIf-gated so it's a no-op in normal CI (no network dependency there). Measured against the most recent ~10k extrinsics + ~10k chain events from production:

Extrinsics: 9722/10000 (97.22%)
Chain events: 9952/10000 (99.52%)
Combined: 19674/20000 (98.37%)

Remaining extrinsic gaps are long-tail calls under ~1% volume each (remove_stake_full_limit, serve_axon, burned_register, transfer_stake, etc.) — deliberately left as null-returning gaps rather than guessed, since I don't have verified real arg shapes for them in this session.

Verification

New tests: 52 cases in chain-summaries.test.ts (one fixture per template family, using the real captured shapes above — including the positional-array cases and both the "found via a template with wrong assumptions" fixes). tsc --noEmit and scoped eslint clean. Full suite: 1626 passed, 1 skipped (the opt-in coverage test) across 206 files.

Verified live via a local dev server against real production data:

• An extrinsic detail page for a real Balances.transfer_keep_alive renders "5FqBL9…Lxoy2s transferred 1.00 τ to 5DxQZ2…7uodow." as the headline, with the raw Balances.transfer_keep_alive still present in the Call field row below.
• /events now reads as a stream of real sentences — "committed time-locked weights, revealing at round X", "Weights were set for SN128", "Transferred X from A to B" — instead of a wall of Pallet.Method labels.
• A real account's "Signed extrinsics" section renders the same sentences per row.

Maintainer PR — reviewed live via a local dev server rather than the contributor screenshot matrix (existing card/table/masthead chrome is unchanged; only the text content inside changes).

[loopover-orb]

Important

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⏳ LoopOver is waiting…

LoopOver has seen this pull request and is waiting on CI checks to finish before reviewing it. This comment will update once the review runs.

_{🟩 Safe / merged · 🟦 Advisory · 🟨 Held for review · 🟥 Blocked / closed · 🟨 Waiting}

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	metagraphed-ui	f2548cf	Commit Preview URL Branch Preview URL	Jul 27 2026, 06:15 PM

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.81%. Comparing base (3ad9a81) to head (f2548cf).
✅ All tests successful. No failed tests found.

Additional details and impacted files

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  Coverage   97.81%   97.81%           
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  Files         419      419           
  Lines       29074    29074           
  Branches    10931    10931           
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  Hits        28440    28440           
  Misses        143      143           
  Partials      491      491           

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