fix: make screenshot uploads retry-safe (#471)

src/main.py

@@ -1,6 +1,7 @@
 import asyncio
 import base64
 import binascii
+import hashlib
 import hmac
 import math
 import os
@@ -2776,20 +2777,40 @@ async def attach_to_assigned_issue(
     owner: str,
     repo: str,
     number: int = PathParam(gt=0),
+    idempotency_key: str | None = Header(default=None, max_length=128),
 ):
     repository = f"{owner}/{repo}"
     try:
         content = attachment.content()
     except ValueError as exc:
         raise HTTPException(status_code=422, detail=str(exc)) from exc
+    async def upload_attachment():
+        result = await gitea_proxy.upload_assigned_issue_attachment(
+            repository,
+            number,
+            attachment.filename,
+            attachment.content_type,
+            content,
+        )
+        safe_name = (
+            result["name"].replace("\\", "\\\\").replace("[", "\\[").replace("]", "\\]")
+            .replace("\r", " ").replace("\n", " ")
+        )
+        safe_url = result["url"].replace("<", "%3C").replace(">", "%3E")
+        result["markdown"] = f"![{safe_name}](<{safe_url}>)"
+        return result
+
     try:
-        result = await asyncio.wait_for(
-            gitea_proxy.upload_assigned_issue_attachment(
+        result = await _run_idempotent_authored_action(
+            upload_attachment(),
+            idempotency_key=idempotency_key,
+            fingerprint=(
+                "issue-attachment",
                 repository,
                 number,
                 attachment.filename,
                 attachment.content_type,
-                content,
+                hashlib.sha256(content).hexdigest(),
             ),
             timeout=ISSUE_ACTION_TIMEOUT_SECONDS,
         )
@@ -2803,12 +2824,6 @@ async def attach_to_assigned_issue(
             status_code=503,
             headers={"Retry-After": "1"},
         )
-    safe_name = (
-        result["name"].replace("\\", "\\\\").replace("[", "\\[").replace("]", "\\]")
-        .replace("\r", " ").replace("\n", " ")
-    )
-    safe_url = result["url"].replace("<", "%3C").replace(">", "%3E")
-    result["markdown"] = f"![{safe_name}](<{safe_url}>)"
     return JSONResponse(result, status_code=201)