Story-2361: Value at stake becomes editable — and the surface learns to say no

The Brief's Value at stake card was a read-only figure. Vega proposed a number, counsel could only look at it. If the framer read ₹4.2 crore out of a quantum statement that actually said ₹42 crore, the Brief carried a wrong figure — the single most consequential number on the page — with no way to correct it in place.

This Story promotes the card: the amount edits in place under numeric validation, and the note beside it (what the figure covers — "principal only", "excluding interest") edits as a plain line.

The one new idea: validation is a PROP AXIS

The frozen vocabulary (docs/design/editable-surface-vocabulary.md §3, founder-ruled on Spike-2316) settles this before anyone can argue it: "Validation is a prop axis, not a kind or preset." The HTML precedent is exact — <input type="number"> is still an <input>. So an amount is not a fifth kind and not a new preset. It is the same EditableField with two extra props:

// src/components/shared/editable-surface.tsx
validate?: (next: string) => boolean;   // false → reject the commit
onInvalid?: (rejected: string) => void; // the caller toasts
inputMode?: "text" | "decimal" | "numeric";

The whole seam lives in one place — the blur commit:

if (next !== current.value) {
  if (current.validate && !current.validate(next)) {
    instance.commands.setContent(...current.value...);  // revert to the last good value
    current.onInvalid?.(next);                          // caller toasts
  } else {
    current.onSave(next);
  }
}

The gate that had to pass first

Every editable-surface Story starts the same way: will the write path actually accept this? For Value at stake the answer is unusual — the amount and the note are written through two different endpoints, and getting that wrong would have shipped a field that looks saved and isn't.

The trap is the amount. It is rendered canonical-first — valueAtStake() in presentation.ts reads brief.canonical.valueAtStake and only falls back to the frame's proposal when the canonical column is empty. So writing the edited amount to the frame would have been swallowed whole: the PATCH succeeds, the frame changes, and the Brief keeps rendering the old canonical figure. The edit vanishes with a green network tab. pramaan-functions says the same thing in its own words:

src/domains/matter_frame/frame_contract.py

# `case_ref`, `value_*`, and `relief_sought` are also Category-1 overlaps but their
# accept is lock-only for now (canonical columns stay primary via their own editors)

What counsel can type

The field displays the formatted figure — ₹4,20,00,000 — so counsel edits what they read. The validator therefore has to accept the rendering it produced, plus the ways a person actually types an amount:

// src/components/matter-detail/brief/presentation.ts
const AMOUNT_NOISE = /[₹,\s]/g;      // the symbol we rendered, INR groups, spaces
const AMOUNT = /^\d+(\.\d{1,2})?$/;  // what must be left over

isAmountValid("₹4,20,00,000")  → true    amountToMinor(...) → 4_200_000_000
isAmountValid("1,25,000.50")   → true    amountToMinor(...) →    12_500_050
isAmountValid("")              → true  (clearing is a legitimate edit → null)
isAmountValid("about 42 crore")→ false   REJECTED — reverts + toasts
isAmountValid("42cr")          → false
isAmountValid("1.234")         → false  (more precision than paise can hold)

Storage is minor units (paise), matching the column: Math.round(major × 100). Clearing the amount clears the currency with it — the pair is one fact, and a currency with no amount is a value at stake nobody can read.

Instant, and reversible

The write is optimistic per AGENTS.md: onMutate patches canonical.valueAtStake in the Brief's TanStack cache so the new figure renders the moment counsel clicks away; the PATCH runs behind it; onError restores the snapshot and toasts; onSettled invalidates to reconcile with server truth. The note rides the frame-edit mutation that already had this exact shape.

The card is now always rendered, empty included — the placeholder is the empty state, the same add-first law as Relief sought and Key instruments. Previously a matter with no value at stake showed no card at all, which is precisely the matter where counsel most needs to type the number in. A non-monetary matter still reads rather than edits: that flag is set where the matter is configured, not on the Brief.

Files

Verification

• pnpm lint — clean (only pre-existing warnings).
• pnpm test — 1242 passing, including the new amount-validation suite in presentation.test.ts (accepts the rendered figure / INR groups / decimals / empty; rejects prose, suffixes, negatives, sub-paise precision; parses to minor units).
• pnpm build — clean.
• Storybook Shared/EditableSurface → NumericValidated — the reject-and-revert interaction, replayable.