diff --git a/src/components/campaign/activity/ActivityResultForm.tsx b/src/components/campaign/activity/ActivityResultForm.tsx
index 26fdb0a4..be0a0f39 100644
--- a/src/components/campaign/activity/ActivityResultForm.tsx
+++ b/src/components/campaign/activity/ActivityResultForm.tsx
@@ -1,7 +1,7 @@
 'use client'
 
 import { useRouter } from 'next/navigation'
-import { useActionState } from 'react'
+import { startTransition, useActionState, type FormEvent } from 'react'
 
 import { registerActivityResultFormAction } from '@/app/(campaign)/campanha/(app)/atividades/[slug]/resultFormActions'
 import { CampaignFormActionMessage } from '@/components/campaign/shared/CampaignFormActionMessage'
@@ -42,6 +42,14 @@ export const ActivityResultForm = ({
         .join(' ')
     : null
 
+  // C139 — manual dispatch: React 19 resets uncontrolled fields after any
+  // settled form action, reverting the typed result to `initialSummary` on
+  // a validation error. `startTransition` keeps `pending` correct.
+  const handleSubmit = (event: FormEvent<HTMLFormElement>) => {
+    event.preventDefault()
+    startTransition(() => formAction(new FormData(event.currentTarget)))
+  }
+
   return (
     <Card>
       <CardHeader>
@@ -49,7 +57,7 @@ export const ActivityResultForm = ({
         {recordedLabel ? <p className="text-sm text-muted-foreground">{recordedLabel}</p> : null}
       </CardHeader>
       <CardContent>
-        <form action={formAction} className="flex flex-col gap-4">
+        <form onSubmit={handleSubmit} className="flex flex-col gap-4">
           <input type="hidden" name="activityId" value={activityId} />
           {state.status !== 'success' ? (
             <CampaignFormActionMessage state={state} errorTitle="Não foi possível registrar" />
diff --git a/src/components/campaign/activity/ActivityUpdateForm.tsx b/src/components/campaign/activity/ActivityUpdateForm.tsx
index d98eaa51..2cd036a6 100644
--- a/src/components/campaign/activity/ActivityUpdateForm.tsx
+++ b/src/components/campaign/activity/ActivityUpdateForm.tsx
@@ -1,7 +1,7 @@
 'use client'
 
 import { useRouter } from 'next/navigation'
-import { useActionState, useRef } from 'react'
+import { startTransition, useActionState, useRef, type FormEvent } from 'react'
 
 import { createActivityUpdateFormAction } from '@/app/(campaign)/campanha/(app)/atividades/[slug]/updateFormActions'
 import { CampaignFormActionMessage } from '@/components/campaign/shared/CampaignFormActionMessage'
@@ -25,13 +25,21 @@ export const ActivityUpdateForm = ({ activityId }: { activityId: number }) => {
 
   const bodyError = fieldError(state.fieldErrors, 'body')
 
+  // C139 — manual dispatch (no `action={formAction}`): React 19 resets
+  // uncontrolled fields after any settled form action, wiping the typed
+  // update on a validation error. `startTransition` keeps `pending` correct.
+  const handleSubmit = (event: FormEvent<HTMLFormElement>) => {
+    event.preventDefault()
+    startTransition(() => formAction(new FormData(event.currentTarget)))
+  }
+
   return (
     <Card>
       <CardHeader>
         <CardTitle>Nova atualização</CardTitle>
       </CardHeader>
       <CardContent>
-        <form ref={formRef} action={formAction} className="flex flex-col gap-4">
+        <form ref={formRef} onSubmit={handleSubmit} className="flex flex-col gap-4">
           <input type="hidden" name="activityId" value={activityId} />
           {state.status !== 'success' ? (
             <CampaignFormActionMessage state={state} errorTitle="Não foi possível enviar" />
diff --git a/src/components/campaign/demand/DemandWorkflowCard.tsx b/src/components/campaign/demand/DemandWorkflowCard.tsx
index 52bdac3d..6d4c8e0c 100644
--- a/src/components/campaign/demand/DemandWorkflowCard.tsx
+++ b/src/components/campaign/demand/DemandWorkflowCard.tsx
@@ -1,6 +1,6 @@
 'use client'
 
-import { useActionState } from 'react'
+import { startTransition, useActionState, type FormEvent } from 'react'
 
 import { Alert, AlertDescription } from '@/components/ui/Alert'
 import { Button } from '@/components/ui/button'
@@ -63,6 +63,19 @@ export const DemandWorkflowCard = ({
       (target !== 'aprovada' && target !== 'rejeitada'),
   )
 
+  // C139 — manual dispatch (no `action={submitTransition}`/`action={submitCost}`):
+  // React 19 resets uncontrolled fields after any settled form action, wiping
+  // the typed decision note and cost on a validation error. `startTransition`
+  // keeps the pending flags correct for the imperative dispatch.
+  const handleTransitionSubmit = (event: FormEvent<HTMLFormElement>) => {
+    event.preventDefault()
+    startTransition(() => submitTransition(new FormData(event.currentTarget)))
+  }
+  const handleCostSubmit = (event: FormEvent<HTMLFormElement>) => {
+    event.preventDefault()
+    startTransition(() => submitCost(new FormData(event.currentTarget)))
+  }
+
   if (readOnly) {
     return (
       <section
@@ -101,7 +114,7 @@ export const DemandWorkflowCard = ({
       </div>
 
       {availableTransitions.length ? (
-        <form action={submitTransition} className="flex flex-col gap-3">
+        <form onSubmit={handleTransitionSubmit} className="flex flex-col gap-3">
           <input type="hidden" name="demandId" value={demandID} />
           <Field>
             <FieldLabel htmlFor={`demand-note-${demandID}`}>Nota da decisão</FieldLabel>
@@ -144,7 +157,7 @@ export const DemandWorkflowCard = ({
         <p className="text-sm text-muted-foreground">Esta demanda já foi decidida.</p>
       )}
 
-      <form action={submitCost} className="flex flex-col gap-2">
+      <form onSubmit={handleCostSubmit} className="flex flex-col gap-2">
         <input type="hidden" name="demandId" value={demandID} />
         <FieldLabel htmlFor={`demand-cost-${demandID}`}>
           Custo estimado (R$) — controle interno
diff --git a/src/components/campaign/municipality/MunicipalityUpdateDeliberation.tsx b/src/components/campaign/municipality/MunicipalityUpdateDeliberation.tsx
index bf47d08c..e9f1135e 100644
--- a/src/components/campaign/municipality/MunicipalityUpdateDeliberation.tsx
+++ b/src/components/campaign/municipality/MunicipalityUpdateDeliberation.tsx
@@ -1,6 +1,6 @@
 'use client'
 
-import { useActionState, useEffect, useRef } from 'react'
+import { startTransition, useActionState, useEffect, useRef, type FormEvent } from 'react'
 
 import { CampaignFormActionMessage } from '@/components/campaign/shared/CampaignFormActionMessage'
 import { Badge } from '@/components/ui/Badge'
@@ -197,6 +197,14 @@ const CommentThread = ({
     if (state.status === 'success' && formRef.current) formRef.current.reset()
   }, [state])
 
+  // C139 — manual dispatch: React 19 resets uncontrolled fields after any
+  // settled form action, wiping the typed comment on a validation error.
+  // The success reset above stays explicit; `startTransition` keeps `pending`.
+  const handleSubmit = (event: FormEvent<HTMLFormElement>) => {
+    event.preventDefault()
+    startTransition(() => submitAction(new FormData(event.currentTarget)))
+  }
+
   return (
     <div className="flex flex-col gap-2">
       <p className="text-sm font-medium">Discussão</p>
@@ -224,7 +232,7 @@ const CommentThread = ({
         </ul>
       ) : null}
       {canComment ? (
-        <form ref={formRef} action={submitAction} className="flex flex-col gap-2">
+        <form ref={formRef} onSubmit={handleSubmit} className="flex flex-col gap-2">
           <input type="hidden" name="updateId" value={updateId} />
           <Textarea
             name="body"