feat(events): the authoring UI proper (Phase 13)

Replaces the two raw JSON boxes Phase 3 shipped as explicit placeholders: a
step's params are a form rendered from the action's own declaration, and a
phase's advance condition is the engagement condition builder. Adds the live cap
meter, the searchable option source's first consumer, and a start dialog
carrying the three fields the route has taken since Phase 10.

One route: POST /admin/events/price, admin+editor. A module's cost() runs on the
server and only there, so a meter has nothing to add up until something asks --
and the dry run is the wrong thing to ask on a debounce twice over: it dispatches
every step through the module and a pass against a version is RECORDED, which is
the stamp K's unattended-start gate reads. This dispatches nothing and records
nothing, and takes the spec in the body because the plan being priced is unsaved
between keystrokes.

A form gives way to JSON on the condition builder's own rule: a value the editor
cannot round-trip is SHOWN rather than silently rewritten. Dropping a param the
action does not declare and flattening `A and (B or C)` are the same mistake.

Two defects fixed in already-merged code:

  * Creating an event has been impossible since Phase 6. `events/new` was added
    beside `events/:id` and binds no param, and React Router ranks a static
    segment above a dynamic one whatever the order -- so the editor was handed no
    id and fetched /admin/events/undefined. Worse, the failure was invisible:
    `!form` is true for every failed load, so the error state sat behind a
    spinner that never stopped.
  * 12b's searchable sources had no consumer. The server half shipped and the
    only UI that reads a source never sent a term, so the 6,707-entry spawner
    list was picked from a 2,000-entry truncation with nothing saying so.

Server: 2113 tests, 2024 pass, 0 fail (89 DB-skipped). Client: 380 pass, 0 fail.
routes:manifest and swagger regenerated -- one route added, none moved.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016wDDVXWMDz82WqE1i969r4

client/src/lib/eventAuthoring.js

@@ -14,6 +14,13 @@
 // meets at 2am while the thing they are trying to stop keeps running — so the
 // guards are written twice on purpose and the copy is checked.
 
+// **The condition builder is borrowed, not rebuilt.** §I says the step editor
+// reuses "the condition builder, exactly" — and a phase's advance gate is
+// literally the engagement grammar, validated on the server by
+// `engagement/conditions.js`. Importing the row helpers is what keeps this screen
+// from becoming a second opinion about a grammar core owns.
+import { conditionRowsFrom, conditionsFromRows, coerceLiteral } from './engagementRules.js'
+
 // A run that is over. Verbatim `eventRuns.db`'s TERMINAL.
 export const TERMINAL_RUN_STATUSES = ['completed', 'cancelled', 'failed', 'missed']
 
@@ -115,14 +122,13 @@ const nextPhaseKey = (phases) => {
 }
 
 /**
- * A new step, with its params box PREFILLED from the action's declared examples.
+ * A new step, with its params PREFILLED from the action's declared examples.
  *
  * Every param carries a required `example` — that requirement is the reason this
- * works — so a fresh `core.announce` step arrives as a JSON object with the right
- * keys and plausible values rather than as an empty `{}` an author has to guess
- * the shape of. It is the nearest a raw JSON box gets to the schema-driven form
- * Phase 13 replaces it with, and it costs nothing the catalog was not already
- * serving.
+ * works — so a fresh `core.announce` step arrives with the right keys and
+ * plausible values rather than empty. Phase 13 turned the box into a form and
+ * this stayed exactly as it was: a form whose fields start at the declared
+ * example is a step an author edits rather than one they compose.
  */
 export function blankStep(action) {
   const params = {}
@@ -152,7 +158,18 @@ export function blankPhase(phases) {
  * typed under the other option is one an operator learns to be afraid of.
  */
 export function blankAdvance() {
-  return { kind: '', after: '30m', on: '', count: 1, whereText: '' }
+  return { kind: '', after: '30m', on: '', count: 1, ...blankWhere() }
+}
+
+/**
+ * The `where` predicate as the BUILDER holds it (Phase 13).
+ *
+ * `whereText` survives beside the rows and is not vestigial: it is what a
+ * predicate the builder cannot render is shown as, and what is posted for one.
+ * See `whereFormFrom`.
+ */
+export function blankWhere() {
+  return { whereOp: 'and', whereRows: [], whereEditable: true, whereText: '' }
 }
 
 export const ADVANCE_KINDS = [
@@ -161,7 +178,7 @@ export const ADVANCE_KINDS = [
   { value: 'on', label: 'When something happens in the game' },
 ]
 
-/** The stored gate, as the form's three fields. */
+/** The stored gate, as the form's fields. */
 export function advanceFormFrom(advance) {
   const blank = blankAdvance()
   if (!advance) return blank
@@ -171,7 +188,34 @@ export function advanceFormFrom(advance) {
     kind: 'on',
     on: advance.on || '',
     count: advance.count ?? 1,
-    whereText: advance.where ? JSON.stringify(advance.where, null, 2) : '',
+    ...whereFormFrom(advance.where),
+  }
+}
+
+/**
+ * A stored `where` tree → the builder's flat rows (Phase 13).
+ *
+ * **This is `conditionRowsFrom` and it is deliberately the same function**, not a
+ * second one shaped like it. The grammar behind a phase gate is the engagement
+ * condition grammar — the server validates it with `engagement/conditions.js`
+ * and renders the diagnosis panel's sentence with the same labels — so an editor
+ * here that re-decided what a tree looks like would be the second implementation
+ * §I refuses on the read side for exactly this reason.
+ *
+ * A tree the flat editor cannot hold (`A and (B or C)`) comes back
+ * `whereEditable: false` and is SHOWN as its JSON rather than silently
+ * flattened: `A and B and C` fires on different events, and an author would have
+ * no way to know the save had done it to them.
+ */
+export function whereFormFrom(where) {
+  const blank = blankWhere()
+  if (!where) return blank
+  const rows = conditionRowsFrom(where)
+  return {
+    whereOp: rows.op,
+    whereRows: rows.rows,
+    whereEditable: rows.editable,
+    whereText: JSON.stringify(where, null, 2),
   }
 }
 
@@ -208,25 +252,37 @@ export function formFromDefinition(event) {
 /**
  * One phase's advance gate, as the spec shape — or null when it has none.
  *
- * Only the `where` JSON is checked, and only because text that is not JSON
- * cannot be put in a request at all. **Whether the predicate is VALID is the
- * server's answer**, and the whole trap of Phase 5 is that it is answered at
- * save with the offending variable named — re-deciding it here would be a second
- * validator drifting from the one that matters, exactly as with a step's params.
+ * **Whether the predicate is VALID is still the server's answer.** The builder
+ * coerces each literal to the type the trigger DECLARED — which is not a second
+ * validator but the thing that makes the first one's error useful: every value
+ * in an HTML input is a string, and `{ cmp: 'gt', value: \"5\" }` against an `int`
+ * variable is refused by `engagement/conditions.js`, rightly, at which point the
+ * author is reading an error about JSON rather than about what they typed.
+ *
+ * A predicate the builder could not render round-trips through `whereText`
+ * unchanged. That is the point of keeping the text: the alternative to posting it
+ * back verbatim is dropping an author's tree because this screen could not draw
+ * it.
  */
-export function advancePayload(advance, where, errors) {
+export function advancePayload(advance, where, errors, variables = []) {
   if (!advance || !advance.kind) return null
   if (advance.kind === 'after') return { after: advance.after }
 
   const out = { on: advance.on, count: Number(advance.count) || 1 }
-  const text = String(advance.whereText || '').trim()
-  if (text) {
-    try {
-      out.where = JSON.parse(text)
-    } catch (err) {
-      errors.push(`${where}, advance condition: ${err.message}`)
+  if (advance.whereEditable === false) {
+    const text = String(advance.whereText || '').trim()
+    if (text) {
+      try {
+        out.where = JSON.parse(text)
+      } catch (err) {
+        errors.push(`${where}, advance condition: ${err.message}`)
+      }
     }
+    return out
   }
+
+  const built = conditionsFromRows(advance.whereOp || 'and', advance.whereRows || [], variables)
+  if (built) out.where = built
   return out
 }
 
@@ -244,10 +300,20 @@ export function advancePayload(advance, where, errors) {
  * applies the action's risk-class default rather than being told a value the
  * form invented.
  */
-export function payloadFromForm(form) {
+export function payloadFromForm(form, { triggersById = new Map() } = {}) {
   const errors = []
   const phases = (form.phases || []).map((phase, pi) => {
-    const where = advancePayload(phase.advance, `Phase ${pi + 1} "${phase.label || phase.key}"`, errors)
+    const where = advancePayload(
+      phase.advance,
+      `Phase ${pi + 1} "${phase.label || phase.key}"`,
+      errors,
+      // The declared types the builder coerces against. A trigger nothing
+      // registers has none, and every literal then stays the string it was typed
+      // as — which is right: the gate is dormant, the server carries its `where`
+      // through unvalidated, and inventing types for it here would edit a
+      // predicate nobody can currently check.
+      triggersById.get(phase.advance?.on)?.variables || [],
+    )
     return {
     key: phase.key,
     label: phase.label,
@@ -431,6 +497,157 @@ export function parseParams(text) {
   return { params: value }
 }
 
+// ── Step params, as a form (Phase 13) ─────────────────────────────
+//
+// §I: the step editor is *"the condition builder, exactly — core serves a
+// catalog, the module declared the schema, core renders a form it does not
+// understand"*. Phase 3 shipped the raw JSON box as an explicit placeholder for
+// this, and everything the form needs was already in the catalog: a param's
+// name, type, whether it is required, its description, its example, and the
+// option source behind it.
+//
+// **The JSON stays as the storage and as the escape hatch, and both halves of
+// that matter.** As storage, because `payloadFromForm` already builds a request
+// out of it and a second representation would be two things to keep in step. As
+// an escape hatch, because a form can only render what the declaration
+// describes — and a step may legitimately hold something it does not.
+//
+// The rule for when the form gives way is the CONDITION BUILDER'S rule, which is
+// the reason this reads as a port of it rather than as a new idea: a value the
+// editor cannot round-trip is SHOWN rather than silently rewritten. Flattening
+// `A and (B or C)` there and dropping an undeclared param here are the same
+// mistake — a save that looks clean and means something else.
+
+/** The two ways a step's params are edited. */
+export const PARAM_FORM = 'form'
+export const PARAM_JSON = 'json'
+
+/**
+ * Can this step's params be rendered as a form without losing anything?
+ *
+ * `{ ok: true }`, or `{ ok: false, reason }` naming what the form cannot hold.
+ * Three things make one, and none of them is an error — each is a step that has
+ * to be edited as JSON:
+ *
+ *   • **the action is dormant.** There is no declaration, so there are no fields.
+ *     A form here would render nothing and look like a step with no params.
+ *   • **a param the action does not declare.** The save refuses it by name, which
+ *     is what the author needs to see — and a form that dropped it would post a
+ *     step that saves cleanly having deleted something they typed.
+ *   • **a value no single control can hold** — an object or an array against a
+ *     scalar declaration.
+ */
+export function paramsRenderable(action, params) {
+  if (!action) return { ok: false, reason: 'the module that registered this action is not installed' }
+  const declared = new Map((action.params || []).map((p) => [p.name, p]))
+  for (const [name, value] of Object.entries(params || {})) {
+    if (!declared.has(name)) {
+      return { ok: false, reason: `this step carries "${name}", which ${action.id} does not declare` }
+    }
+    if (value !== null && typeof value === 'object') {
+      return { ok: false, reason: `"${name}" holds a ${Array.isArray(value) ? 'list' : 'structure'}, which no single field can hold` }
+    }
+  }
+  return { ok: true }
+}
+
+/**
+ * Which mode should this step open in?
+ *
+ * The author's own choice wins whenever the form COULD render the step — an
+ * author who switched to JSON stays in JSON. What they cannot do is stay in a
+ * form that would lose something, so an unrenderable step is forced to JSON
+ * whatever the choice was, and the reason is returned so the screen can say it.
+ */
+export function paramsMode(step, action) {
+  const parsed = parseParams(step?.paramsText)
+  if (parsed.error) return { mode: PARAM_JSON, forced: true, reason: parsed.error }
+  const renderable = paramsRenderable(action, parsed.params)
+  if (!renderable.ok) return { mode: PARAM_JSON, forced: true, reason: renderable.reason }
+  return { mode: step?.paramsMode === PARAM_JSON ? PARAM_JSON : PARAM_FORM, forced: false, reason: null }
+}
+
+/** One declared param's current value, as the control holds it. */
+export function paramValue(step, name) {
+  const parsed = parseParams(step?.paramsText)
+  if (parsed.error) return undefined
+  return parsed.params[name]
+}
+
+/**
+ * Write one param, and give back the whole box.
+ *
+ * **An empty field REMOVES the key rather than posting an empty string**, and
+ * that is the server's own reading rather than a convenience: `checkParams`
+ * treats `undefined`, `null` and `''` alike — absent — so a required param left
+ * blank comes back as *"is required"*, which is the error the author needs,
+ * instead of as a type complaint about `""`.
+ *
+ * **A value that does not parse is passed through as typed.** `coerceLiteral` is
+ * the engagement builder's, unchanged, and its rule is the one that matters
+ * here too: half of `-` is not a number, and turning it into `NaN` or `0` while
+ * somebody is still typing would either post a value they never wrote or make
+ * the field impossible to type a negative into. The server's type check then
+ * names the param.
+ *
+ * Re-serialising the whole object rather than splicing text, for `pickParam`'s
+ * reason: a string edit that produced valid-looking JSON with a duplicate key
+ * would be a value the editor and the server read differently.
+ */
+export function setParam(step, name, raw, type) {
+  const parsed = parseParams(step?.paramsText)
+  if (parsed.error) return step?.paramsText || '{}'
+  const next = { ...parsed.params }
+  if (raw === '' || raw === undefined || raw === null) delete next[name]
+  else next[name] = coerceLiteral(type, raw)
+  return JSON.stringify(next, null, 2)
+}
+
+/**
+ * A stored `datetime` as a `datetime-local` input wants it, and back.
+ *
+ * The server normalises a datetime param to an ISO string (`conditions.js`
+ * `checkLiteral`), and the input needs `YYYY-MM-DDTHH:mm` with no zone. The
+ * slice is the whole conversion in one direction; in the other the input's own
+ * text is a moment `new Date()` parses, so it is posted as typed and the server
+ * does the normalising — one implementation of what a datetime is, and it is
+ * not this one.
+ */
+export const datetimeInputValue = (value) => (typeof value === 'string' ? value.slice(0, 16) : '')
+
+/**
+ * Everything the meter needs out of the form, and nothing else.
+ *
+ * The price route takes a spec, not a definition: no title, no schedule, no
+ * series. Sending the whole payload would put a document in front of a route
+ * that reads two fields of it — and would fail the moment the rest of the form
+ * is mid-edit, which is exactly when the meter is being read.
+ *
+ * A step whose params do not parse is sent with none rather than dropped, so a
+ * half-typed JSON box costs its own step's draw and not the phase's.
+ */
+export function priceBodyFrom(form) {
+  return {
+    phases: (form?.phases || []).map((phase) => ({
+      key: phase.key || null,
+      steps: (phase.steps || []).map((step) => ({
+        actionId: step.actionId || '',
+        params: parseParams(step.paramsText).params || {},
+      })),
+    })),
+  }
+}
+
+/**
+ * Is this plan worth pricing at all?
+ *
+ * A meter that fires on an empty form asks the server what nothing costs, on
+ * every keystroke of the title field. One step with an action chosen is the
+ * threshold, because that is the first moment there is an answer.
+ */
+export const worthPricing = (form) =>
+  (form?.phases || []).some((p) => (p.steps || []).some((s) => s.actionId))
+
 // ── Rendering what happened ────────────────────────────────────────────────
 
 const STATUS_WORDS = {