Add Boolean param kind that is always present true/false (ticket 018)

MetricPrimitiveKind gains Boolean, serialized as "boolean". A param
declared with kind Boolean skips capture-group validation and, instead
of being omitted when message_match_regex doesn't match, is present on
every log line as true/false based purely on whether the regex matches
(case-insensitively or per the regex's own flags). Params.tsx lets you
pick boolean as a kind and disables the now-unused capture group input.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XFUNZwCvz3kcod3352ZR2o

webapp/src/components/Params.tsx

@@ -14,12 +14,15 @@ export function Params({ params, onDeclared }: { params: ParamDeclaration[]; onD
   const [submitting, setSubmitting] = useState(false)
   const [collapsed, setCollapsed] = useSectionCollapsed('params')
 
+  const isBoolean = kind === 'boolean'
+
   async function handleSubmit(e: React.FormEvent) {
     e.preventDefault()
     setSubmitError(null)
     setSubmitting(true)
     try {
-      await declareParam({ name, message_match_regex: regex, capture_group: captureGroup, kind })
+      // A boolean-kind param never uses a capture group — its value is just whether the regex matched.
+      await declareParam({ name, message_match_regex: regex, capture_group: isBoolean ? '' : captureGroup, kind })
       setName('')
       setRegex('')
       setCaptureGroup('')
@@ -68,13 +71,16 @@ export function Params({ params, onDeclared }: { params: ParamDeclaration[]; onD
           </div>
           <div className="flex items-end gap-1">
             <div className="min-w-0 flex-1">
-              <label className="mb-1 block text-xs text-text-subtle">Capture group</label>
+              <label className="mb-1 block text-xs text-text-subtle">
+                Capture group{isBoolean && ' (unused for boolean)'}
+              </label>
               <input
-                className="w-full min-w-0 rounded border border-border-soft bg-surface-1 px-1.5 py-1 text-xs text-text placeholder:text-text-subtle focus:border-border-strong focus:outline-none"
+                className="w-full min-w-0 rounded border border-border-soft bg-surface-1 px-1.5 py-1 text-xs text-text placeholder:text-text-subtle focus:border-border-strong focus:outline-none disabled:opacity-50"
                 value={captureGroup}
                 onChange={(e) => setCaptureGroup(e.target.value)}
                 placeholder="path"
-                required
+                required={!isBoolean}
+                disabled={isBoolean}
               />
             </div>
             <select
@@ -86,6 +92,7 @@ export function Params({ params, onDeclared }: { params: ParamDeclaration[]; onD
               <option value="number">number</option>
               <option value="timestamp">timestamp</option>
               <option value="duration">duration</option>
+              <option value="boolean">boolean</option>
             </select>
           </div>
           {submitError && <div className="rounded border border-danger-border bg-danger-bg/50 px-2 py-1 text-xs text-danger-text">{submitError}</div>}
@@ -108,7 +115,7 @@ export function Params({ params, onDeclared }: { params: ParamDeclaration[]; onD
                 className="rounded border border-border-soft px-2 py-1 text-xs text-text-secondary"
                 title={p.message_match_regex}
               >
-                {p.name} ({p.kind}, group {p.capture_group})
+                {p.name} ({p.kind}{p.kind === 'boolean' ? '' : `, group ${p.capture_group}`})
               </span>
             ))}
           </div>

webapp/src/lib/api.ts

@@ -4,11 +4,13 @@ export type MetricPrimitive =
   | { Number: { Int: number } | { Float: number } }
   | { Timestamp: number }
   | { Duration: number }
+  | { Boolean: boolean }
 
 export function metricPrimitiveToDisplayString(value: MetricPrimitive): string {
   if ('String' in value) return value.String
   if ('Timestamp' in value) return String(value.Timestamp)
   if ('Duration' in value) return `${value.Duration}ms`
+  if ('Boolean' in value) return String(value.Boolean)
   if ('Int' in value.Number) return String(value.Number.Int)
   return String(value.Number.Float)
 }
@@ -25,7 +27,7 @@ export interface ParamDeclaration {
   name: string
   message_match_regex: string
   capture_group: string
-  kind: 'string' | 'number' | 'timestamp' | 'duration'
+  kind: 'string' | 'number' | 'timestamp' | 'duration' | 'boolean'
 }
 
 export interface TimelineBucket {