diff --git a/apps/sim/lib/copilot/chat/payload.test.ts b/apps/sim/lib/copilot/chat/payload.test.ts
index f4c3f802ef5..92e77ffb63a 100644
--- a/apps/sim/lib/copilot/chat/payload.test.ts
+++ b/apps/sim/lib/copilot/chat/payload.test.ts
@@ -316,7 +316,12 @@ describe('buildCopilotRequestPayload', () => {
       workspaceId: 'ws-1',
       chatId: 'chat-1',
       fileAttachments: [
-        { id: 'a1', key: 'workspace/ws-1/1731000000000-ab12cd34-payroll.xlsx', size: 1 },
+        {
+          id: 'a1',
+          key: 'workspace/ws-1/1731000000000-ab12cd34-payroll.xlsx',
+          filename: 'payroll.xlsx',
+          size: 1,
+        },
       ],
     }
 
@@ -350,6 +355,39 @@ describe('buildCopilotRequestPayload', () => {
         'msg-1'
       )
     })
+
+    it('includes successfully prepared attachments in the model context', async () => {
+      const payload = await buildCopilotRequestPayload(
+        { ...attachmentParams, userPermission: 'write' },
+        { selectedModel: 'claude-opus-4-8' }
+      )
+
+      expect(payload.context).toEqual([
+        {
+          type: 'uploaded_file',
+          content: [
+            'File "payroll.xlsx" (application/octet-stream, 1 bytes) uploaded.',
+            'Read with: read("uploads/payroll.xlsx")',
+            'To save permanently: materialize_file(fileName: "payroll.xlsx")',
+          ].join('\n'),
+        },
+      ])
+    })
+
+    it('fails the request when an authorized attachment cannot be prepared', async () => {
+      const cause = new Error('provenance sidecar unavailable')
+      mockTrackChatUpload.mockRejectedValueOnce(cause)
+
+      await expect(
+        buildCopilotRequestPayload(
+          { ...attachmentParams, userPermission: 'write' },
+          { selectedModel: 'claude-opus-4-8' }
+        )
+      ).rejects.toMatchObject({
+        message: 'Failed to prepare attached file "payroll.xlsx" for Copilot. Please try again.',
+        cause,
+      })
+    })
   })
 
   it('passes workspaceContext through to the Go request payload', async () => {
diff --git a/apps/sim/lib/copilot/chat/payload.ts b/apps/sim/lib/copilot/chat/payload.ts
index 3f8c138ab16..7c9988ddac4 100644
--- a/apps/sim/lib/copilot/chat/payload.ts
+++ b/apps/sim/lib/copilot/chat/payload.ts
@@ -395,11 +395,16 @@ export async function buildCopilotRequestPayload(
           content: lines.join('\n'),
         })
       } catch (err) {
+        const cause = toError(err)
         logger.warn('Failed to track chat upload', {
           filename,
           chatId,
-          error: toError(err).message,
+          error: cause.message,
         })
+        throw new Error(
+          `Failed to prepare attached file "${filename}" for Copilot. Please try again.`,
+          { cause }
+        )
       }
     }
   }
diff --git a/apps/sim/lib/uploads/contexts/workspace/workspace-file-secret-provenance.test.ts b/apps/sim/lib/uploads/contexts/workspace/workspace-file-secret-provenance.test.ts
index a487ee9473a..e941cdf6047 100644
--- a/apps/sim/lib/uploads/contexts/workspace/workspace-file-secret-provenance.test.ts
+++ b/apps/sim/lib/uploads/contexts/workspace/workspace-file-secret-provenance.test.ts
@@ -136,7 +136,7 @@ describe('workspace file secret provenance', () => {
     )
   })
 
-  it('treats only canonically bound untouched legacy files as model-safe without a sidecar', async () => {
+  it('classifies attachments by their canonical storage key without requiring a database file id', async () => {
     queueTableRows(workspaceFiles, [
       {
         id: 'safe-id',
@@ -219,9 +219,11 @@ describe('workspace file secret provenance', () => {
 
     const attachments = [
       { id: 'safe-id', key: 'safe-key' },
+      { key: 'safe-key' },
+      { id: 'file-1700000000000', key: 'safe-key' },
       { id: 'tracked-no-sidecar-id', key: 'tracked-no-sidecar-key' },
       { id: 'wrong-id', key: 'safe-key' },
-      { id: 'tainted-id', key: 'tainted-key' },
+      { id: 'safe-id', key: 'tainted-key' },
       { id: 'unknown-id', key: 'unknown-key' },
       { id: 'other-workspace-id', key: 'other-workspace-key' },
       { id: 'pre-marker-sidecar-id', key: 'pre-marker-sidecar-key' },
@@ -234,6 +236,9 @@ describe('workspace file secret provenance', () => {
       filterModelSafeWorkspaceFileAttachments(attachments, { workspaceId: 'workspace-1' })
     ).resolves.toEqual([
       { id: 'safe-id', key: 'safe-key' },
+      { key: 'safe-key' },
+      { id: 'file-1700000000000', key: 'safe-key' },
+      { id: 'wrong-id', key: 'safe-key' },
       { id: 'pre-marker-sidecar-id', key: 'pre-marker-sidecar-key' },
       { id: 'synthetic-execution-id', key: 'untracked-context-key' },
       { id: 'legacy-id', key: 'legacy-key' },
diff --git a/apps/sim/lib/uploads/contexts/workspace/workspace-file-secret-provenance.ts b/apps/sim/lib/uploads/contexts/workspace/workspace-file-secret-provenance.ts
index 0437d0487b4..7366378e270 100644
--- a/apps/sim/lib/uploads/contexts/workspace/workspace-file-secret-provenance.ts
+++ b/apps/sim/lib/uploads/contexts/workspace/workspace-file-secret-provenance.ts
@@ -60,7 +60,6 @@ export interface WorkspaceFileSecretProvenanceEnvelope<T> {
 }
 
 interface ModelSafeWorkspaceFileRow {
-  id: string
   key: string
   workspaceId: string | null
   context: string
@@ -543,9 +542,12 @@ export async function importWorkspaceFileSecretProvenanceForRuntime(args: {
 }
 
 /**
- * Removes model attachments whose canonical workspace-file record is tainted, unknown, or does
- * not match the supplied file id. Missing legacy records remain compatible; any persisted record
- * is classified exclusively by its trusted key/id binding and private provenance row.
+ * Removes model attachments whose canonical workspace-file record is tainted or unknown.
+ * Missing legacy records remain compatible; persisted records are classified by their unique
+ * active storage-key binding and private provenance row. Attachment ids are deliberately ignored:
+ * older persisted workflows omit them and file normalization may synthesize a runtime-only id.
+ * This classification is not file authorization; callers still enforce storage access before
+ * reading bytes or issuing a provider URL.
  */
 export async function filterModelSafeWorkspaceFileAttachments<
   TAttachment extends WorkspaceFileAttachmentIdentity,
@@ -567,24 +569,7 @@ export async function filterModelSafeWorkspaceFileAttachments<
   ]
   if (keys.length === 0) return [...attachments]
 
-  const rows = await db
-    .select({
-      id: workspaceFiles.id,
-      key: workspaceFiles.key,
-      workspaceId: workspaceFiles.workspaceId,
-      context: workspaceFiles.context,
-      fileContentUpdatedAt: workspaceFiles.contentUpdatedAt,
-      secretProvenanceVersion: workspaceFiles.secretProvenanceVersion,
-      provenanceContentUpdatedAt: workspaceFileSecretProvenance.contentUpdatedAt,
-      status: workspaceFileSecretProvenance.status,
-      entries: workspaceFileSecretProvenance.entries,
-    })
-    .from(workspaceFiles)
-    .leftJoin(
-      workspaceFileSecretProvenance,
-      eq(workspaceFileSecretProvenance.fileId, workspaceFiles.id)
-    )
-    .where(and(inArray(workspaceFiles.key, keys), isNull(workspaceFiles.deletedAt)))
+  const rows = await loadModelSafeWorkspaceFileRows(keys)
 
   const rowByKey = new Map(rows.map((row) => [row.key, row]))
   return attachments.filter((attachment) => {
@@ -592,7 +577,6 @@ export async function filterModelSafeWorkspaceFileAttachments<
     const row = rowByKey.get(attachment.key)
     if (!row) return true
     if (row.context !== 'workspace' && row.context !== 'mothership') return true
-    if (typeof attachment.id !== 'string' || attachment.id !== row.id) return false
     return isModelSafeWorkspaceFileRow(row, options.workspaceId)
   })
 }
@@ -614,6 +598,28 @@ function isModelSafeWorkspaceFileRow(
   return row.entries.length === 0
 }
 
+async function loadModelSafeWorkspaceFileRows(
+  keys: readonly string[]
+): Promise<ModelSafeWorkspaceFileRow[]> {
+  return db
+    .select({
+      key: workspaceFiles.key,
+      workspaceId: workspaceFiles.workspaceId,
+      context: workspaceFiles.context,
+      fileContentUpdatedAt: workspaceFiles.contentUpdatedAt,
+      secretProvenanceVersion: workspaceFiles.secretProvenanceVersion,
+      provenanceContentUpdatedAt: workspaceFileSecretProvenance.contentUpdatedAt,
+      status: workspaceFileSecretProvenance.status,
+      entries: workspaceFileSecretProvenance.entries,
+    })
+    .from(workspaceFiles)
+    .leftJoin(
+      workspaceFileSecretProvenance,
+      eq(workspaceFileSecretProvenance.fileId, workspaceFiles.id)
+    )
+    .where(and(inArray(workspaceFiles.key, [...keys]), isNull(workspaceFiles.deletedAt)))
+}
+
 /**
  * Verifies a server-authorized storage key before its bytes or signed URL cross a model boundary.
  * Unlike attachment filtering, the key has already passed access control, so no caller-provided
@@ -642,24 +648,7 @@ export async function areModelSafeWorkspaceFileKeys(
     throw new Error('Too many file keys to verify secret provenance')
   }
 
-  const rows = await db
-    .select({
-      id: workspaceFiles.id,
-      key: workspaceFiles.key,
-      workspaceId: workspaceFiles.workspaceId,
-      context: workspaceFiles.context,
-      fileContentUpdatedAt: workspaceFiles.contentUpdatedAt,
-      secretProvenanceVersion: workspaceFiles.secretProvenanceVersion,
-      provenanceContentUpdatedAt: workspaceFileSecretProvenance.contentUpdatedAt,
-      status: workspaceFileSecretProvenance.status,
-      entries: workspaceFileSecretProvenance.entries,
-    })
-    .from(workspaceFiles)
-    .leftJoin(
-      workspaceFileSecretProvenance,
-      eq(workspaceFileSecretProvenance.fileId, workspaceFiles.id)
-    )
-    .where(and(inArray(workspaceFiles.key, uniqueKeys), isNull(workspaceFiles.deletedAt)))
+  const rows = await loadModelSafeWorkspaceFileRows(uniqueKeys)
 
   return rows.every(
     (row) =>