diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 4840935..7b48216 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -4,7 +4,6 @@ on:
   push:
     branches: [main]
   pull_request:
-    branches: [main]
 
 jobs:
   build-and-test:
diff --git a/abis/RecurringCollector.json b/abis/RecurringCollector.json
index 702cba3..7ba7df2 100644
--- a/abis/RecurringCollector.json
+++ b/abis/RecurringCollector.json
@@ -59,5 +59,16 @@
     ],
     "name": "RCACollected",
     "type": "event"
+  },
+  {
+    "anonymous": false,
+    "inputs": [
+      { "indexed": true, "name": "agreementId", "type": "bytes16" },
+      { "indexed": true, "name": "payer", "type": "address" },
+      { "indexed": true, "name": "offerType", "type": "uint8" },
+      { "indexed": false, "name": "offerHash", "type": "bytes32" }
+    ],
+    "name": "OfferStored",
+    "type": "event"
   }
 ]
diff --git a/schema.graphql b/schema.graphql
index 2e88a21..1179435 100644
--- a/schema.graphql
+++ b/schema.graphql
@@ -71,3 +71,23 @@ type IndexerDeploymentLatest @entity(immutable: false) {
   blockNumber: BigInt!
   blockTimestamp: BigInt!
 }
+
+# First stored offer per agreementId, keyed by bytes16 agreement ID.
+# Dipper queries this entity as an idempotency gate -- avoids re-submitting
+# an offer after a crashed-mid-flight restart where the on-chain tx landed
+# but dipper lost track of it.
+#
+# Declared immutable because, for a given agreementId, the RCA identifying
+# fields (payer, dataService, serviceProvider, deadline, nonce) are fixed by
+# the id derivation, so any duplicate OfferStored event for the same id would
+# carry the same offerHash. The handler enforces this by returning early on
+# the second event instead of attempting to overwrite.
+type Offer @entity(immutable: true) {
+  id: Bytes!
+  payer: Bytes!
+  offerType: Int!
+  offerHash: Bytes!
+  createdAtBlock: BigInt!
+  createdAtTimestamp: BigInt!
+  createdAtTx: Bytes!
+}
diff --git a/src/recurringCollector.ts b/src/recurringCollector.ts
index 32348d2..5dc67ed 100644
--- a/src/recurringCollector.ts
+++ b/src/recurringCollector.ts
@@ -1,9 +1,10 @@
-import { IndexingAgreement } from '../generated/schema'
+import { IndexingAgreement, Offer } from '../generated/schema'
 import {
   AgreementAccepted,
   AgreementCanceled,
   AgreementUpdated,
   RCACollected,
+  OfferStored as OfferStoredEvent,
 } from '../generated/RecurringCollector/RecurringCollector'
 import { createOrLoadIndexingAgreement, BIGINT_ZERO } from './helpers'
 
@@ -61,3 +62,24 @@ export function handleRCACollected(event: RCACollected): void {
   agreement.tokensCollected = agreement.tokensCollected.plus(event.params.tokens)
   agreement.save()
 }
+
+export function handleOfferStored(event: OfferStoredEvent): void {
+  // First-offer entity keyed by agreementId (bytes16). Immutable: if an
+  // entity already exists, a duplicate OfferStored event for the same
+  // agreement id (e.g. dipper crashed and re-submitted, or a chain reorg
+  // re-emitted) carries the same offerHash by construction and we return
+  // early. Writing to an immutable entity a second time is a graph-node
+  // error that would halt the subgraph, so the guard is load-bearing.
+  let existing = Offer.load(event.params.agreementId)
+  if (existing != null) {
+    return
+  }
+  let offer = new Offer(event.params.agreementId)
+  offer.payer = event.params.payer
+  offer.offerType = event.params.offerType
+  offer.offerHash = event.params.offerHash
+  offer.createdAtBlock = event.block.number
+  offer.createdAtTimestamp = event.block.timestamp
+  offer.createdAtTx = event.transaction.hash
+  offer.save()
+}
diff --git a/subgraph.template.yaml b/subgraph.template.yaml
index 1d7f146..43263f8 100644
--- a/subgraph.template.yaml
+++ b/subgraph.template.yaml
@@ -43,6 +43,7 @@ dataSources:
       language: wasm/assemblyscript
       entities:
         - IndexingAgreement
+        - Offer
       abis:
         - name: RecurringCollector
           file: ./abis/RecurringCollector.json
@@ -59,4 +60,6 @@ dataSources:
         - event: RCACollected(indexed address,indexed address,indexed address,bytes16,bytes32,uint256,uint256)
           handler: handleRCACollected
           topic1: ["{{subgraphServiceAddress}}"]
+        - event: OfferStored(indexed bytes16,indexed address,indexed uint8,bytes32)
+          handler: handleOfferStored
       file: ./src/recurringCollector.ts
diff --git a/tests/recurringCollector.test.ts b/tests/recurringCollector.test.ts
new file mode 100644
index 0000000..aecd44c
--- /dev/null
+++ b/tests/recurringCollector.test.ts
@@ -0,0 +1,67 @@
+import { assert, describe, test, clearStore, afterEach, newMockEvent } from 'matchstick-as'
+import { Address, Bytes, BigInt, ethereum } from '@graphprotocol/graph-ts'
+import { handleOfferStored } from '../src/recurringCollector'
+import { OfferStored as OfferStoredEvent } from '../generated/RecurringCollector/RecurringCollector'
+
+const PAYER = Address.fromString('0x0000000000000000000000000000000000000002')
+const AGREEMENT_ID = Bytes.fromHexString('0x0102030405060708090a0b0c0d0e0f10')
+
+function createOfferStoredEvent(
+  agreementId: Bytes,
+  offerType: i32,
+  offerHash: Bytes,
+): OfferStoredEvent {
+  let event = changetype<OfferStoredEvent>(newMockEvent())
+
+  event.parameters = new Array()
+  event.parameters.push(
+    new ethereum.EventParam('agreementId', ethereum.Value.fromFixedBytes(agreementId)),
+  )
+  event.parameters.push(new ethereum.EventParam('payer', ethereum.Value.fromAddress(PAYER)))
+  event.parameters.push(
+    new ethereum.EventParam(
+      'offerType',
+      ethereum.Value.fromUnsignedBigInt(BigInt.fromI32(offerType)),
+    ),
+  )
+  event.parameters.push(
+    new ethereum.EventParam('offerHash', ethereum.Value.fromFixedBytes(offerHash)),
+  )
+
+  return event
+}
+
+describe('handleOfferStored', () => {
+  afterEach(() => {
+    clearStore()
+  })
+
+  test('first event creates Offer entity', () => {
+    let offerHash = Bytes.fromHexString('0x' + 'aa'.repeat(32))
+    let event = createOfferStoredEvent(AGREEMENT_ID, 0, offerHash)
+    handleOfferStored(event)
+
+    assert.entityCount('Offer', 1)
+
+    let id = AGREEMENT_ID.toHexString()
+    assert.fieldEquals('Offer', id, 'payer', PAYER.toHexString())
+    assert.fieldEquals('Offer', id, 'offerType', '0')
+    assert.fieldEquals('Offer', id, 'offerHash', offerHash.toHexString())
+  })
+
+  test('duplicate event for same agreementId is a no-op (idempotency guard)', () => {
+    let offerHash = Bytes.fromHexString('0x' + 'aa'.repeat(32))
+
+    let event1 = createOfferStoredEvent(AGREEMENT_ID, 0, offerHash)
+    handleOfferStored(event1)
+
+    // Second event for same agreementId must not halt on immutable re-write.
+    let event2 = createOfferStoredEvent(AGREEMENT_ID, 0, offerHash)
+    event2.transaction.hash = Bytes.fromHexString(
+      '0x1111111111111111111111111111111111111111111111111111111111111111',
+    ) as Bytes
+    handleOfferStored(event2)
+
+    assert.entityCount('Offer', 1)
+  })
+})