feat: add get_archive_by_id endpoint [LET-4405] (#5640)

add get_archive_by_id

Co-authored-by: Ari Webb <ari@letta.com>

fern/openapi.json

@@ -200,6 +200,51 @@
       }
     },
     "/v1/archives/{archive_id}": {
+      "get": {
+        "tags": ["archives"],
+        "summary": "Get Archive By Id",
+        "description": "Get a single archive by its ID.",
+        "operationId": "get_archive_by_id",
+        "parameters": [
+          {
+            "name": "archive_id",
+            "in": "path",
+            "required": true,
+            "schema": {
+              "type": "string",
+              "minLength": 44,
+              "maxLength": 44,
+              "pattern": "^archive-[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$",
+              "description": "The ID of the archive in the format 'archive-<uuid4>'",
+              "examples": ["archive-123e4567-e89b-42d3-8456-426614174000"],
+              "title": "Archive Id"
+            },
+            "description": "The ID of the archive in the format 'archive-<uuid4>'"
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "Successful Response",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/Archive"
+                }
+              }
+            }
+          },
+          "422": {
+            "description": "Validation Error",
+            "content": {
+              "application/json": {
+                "schema": {
+                  "$ref": "#/components/schemas/HTTPValidationError"
+                }
+              }
+            }
+          }
+        }
+      },
       "patch": {
         "tags": ["archives"],
         "summary": "Modify Archive",

letta/server/rest_api/routers/v1/archives.py

@@ -83,6 +83,22 @@ async def list_archives(
     return archives
 
 
+@router.get("/{archive_id}", response_model=PydanticArchive, operation_id="get_archive_by_id")
+async def get_archive_by_id(
+    archive_id: ArchiveId,
+    server: "SyncServer" = Depends(get_letta_server),
+    headers: HeaderParams = Depends(get_headers),
+):
+    """
+    Get a single archive by its ID.
+    """
+    actor = await server.user_manager.get_actor_or_default_async(actor_id=headers.actor_id)
+    return await server.archive_manager.get_archive_by_id_async(
+        archive_id=archive_id,
+        actor=actor,
+    )
+
+
 @router.patch("/{archive_id}", response_model=PydanticArchive, operation_id="modify_archive")
 async def modify_archive(
     archive_id: ArchiveId,