diff --git a/.github/workflows/pyrefly-diff-comment.yml b/.github/workflows/pyrefly-diff-comment.yml
new file mode 100644
index 0000000000..b9790945f9
--- /dev/null
+++ b/.github/workflows/pyrefly-diff-comment.yml
@@ -0,0 +1,88 @@
+name: Comment with Pyrefly Diff
+
+on:
+  workflow_run:
+    workflows:
+      - Pyrefly Diff Check
+    types:
+      - completed
+
+permissions: {}
+
+jobs:
+  comment:
+    name: Comment PR with pyrefly diff
+    runs-on: ubuntu-latest
+    permissions:
+      actions: read
+      contents: read
+      issues: write
+      pull-requests: write
+    if: ${{ github.event.workflow_run.conclusion == 'success' && github.event.workflow_run.pull_requests[0].head.repo.full_name != github.repository }}
+    steps:
+      - name: Download pyrefly diff artifact
+        uses: actions/github-script@v8
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const fs = require('fs');
+            const artifacts = await github.rest.actions.listWorkflowRunArtifacts({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              run_id: ${{ github.event.workflow_run.id }},
+            });
+            const match = artifacts.data.artifacts.find((artifact) =>
+              artifact.name === 'pyrefly_diff'
+            );
+            if (!match) {
+              throw new Error('pyrefly_diff artifact not found');
+            }
+            const download = await github.rest.actions.downloadArtifact({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              artifact_id: match.id,
+              archive_format: 'zip',
+            });
+            fs.writeFileSync('pyrefly_diff.zip', Buffer.from(download.data));
+
+      - name: Unzip artifact
+        run: unzip -o pyrefly_diff.zip
+
+      - name: Post comment
+        uses: actions/github-script@v8
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const fs = require('fs');
+            let diff = fs.readFileSync('pyrefly_diff.txt', { encoding: 'utf8' });
+            let prNumber = null;
+            try {
+              prNumber = parseInt(fs.readFileSync('pr_number.txt', { encoding: 'utf8' }), 10);
+            } catch (err) {
+              // Fallback to workflow_run payload if artifact is missing or incomplete.
+              const prs = context.payload.workflow_run.pull_requests || [];
+              if (prs.length > 0 && prs[0].number) {
+                prNumber = prs[0].number;
+              }
+            }
+            if (!prNumber) {
+              throw new Error('PR number not found in artifact or workflow_run payload');
+            }
+
+            const MAX_CHARS = 65000;
+            if (diff.length > MAX_CHARS) {
+              diff = diff.slice(0, MAX_CHARS);
+              diff = diff.slice(0, diff.lastIndexOf('\\n'));
+              diff += '\\n\\n... (truncated) ...';
+            }
+
+            const body = diff.trim()
+              ? `### Pyrefly Diff (base → PR)\\n\\`\\`\\`diff\\n${diff}\\n\\`\\`\\``
+              : '### Pyrefly Diff\\nNo changes detected.';
+
+            await github.rest.issues.createComment({
+              issue_number: prNumber,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body,
+            });
diff --git a/.github/workflows/pyrefly-diff.yml b/.github/workflows/pyrefly-diff.yml
new file mode 100644
index 0000000000..7dc407c11c
--- /dev/null
+++ b/.github/workflows/pyrefly-diff.yml
@@ -0,0 +1,85 @@
+name: Pyrefly Diff Check
+
+on:
+  pull_request:
+    paths:
+      - 'api/**/*.py'
+
+permissions:
+  contents: read
+
+jobs:
+  pyrefly-diff:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      issues: write
+      pull-requests: write
+    steps:
+      - name: Checkout PR branch
+        uses: actions/checkout@v6
+        with:
+          fetch-depth: 0
+
+      - name: Setup Python & UV
+        uses: astral-sh/setup-uv@v5
+        with:
+          enable-cache: true
+
+      - name: Install dependencies
+        run: uv sync --project api --dev
+
+      - name: Run pyrefly on PR branch
+        run: |
+          uv run --directory api pyrefly check > /tmp/pyrefly_pr.txt 2>&1 || true
+
+      - name: Checkout base branch
+        run: git checkout ${{ github.base_ref }}
+
+      - name: Run pyrefly on base branch
+        run: |
+          uv run --directory api pyrefly check > /tmp/pyrefly_base.txt 2>&1 || true
+
+      - name: Compute diff
+        run: |
+          diff /tmp/pyrefly_base.txt /tmp/pyrefly_pr.txt > pyrefly_diff.txt || true
+
+      - name: Save PR number
+        run: |
+          echo ${{ github.event.pull_request.number }} > pr_number.txt
+
+      - name: Upload pyrefly diff
+        uses: actions/upload-artifact@v4
+        with:
+          name: pyrefly_diff
+          path: |
+            pyrefly_diff.txt
+            pr_number.txt
+
+      - name: Comment PR with pyrefly diff
+        if: ${{ github.event.pull_request.head.repo.full_name == github.repository }}
+        uses: actions/github-script@v8
+        with:
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+          script: |
+            const fs = require('fs');
+            let diff = fs.readFileSync('pyrefly_diff.txt', { encoding: 'utf8' });
+            const prNumber = context.payload.pull_request.number;
+
+            const MAX_CHARS = 65000;
+            if (diff.length > MAX_CHARS) {
+              diff = diff.slice(0, MAX_CHARS);
+              diff = diff.slice(0, diff.lastIndexOf('\n'));
+              diff += '\n\n... (truncated) ...';
+            }
+
+            const body = diff.trim()
+              ? `### Pyrefly Diff (base → PR)\n\`\`\`diff\n${diff}\n\`\`\``
+              : '### Pyrefly Diff\nNo changes detected.';
+
+            await github.rest.issues.createComment({
+              issue_number: prNumber,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body,
+            });
diff --git a/api/extensions/storage/aws_s3_storage.py b/api/extensions/storage/aws_s3_storage.py
index 6ab2a95e3c..978f60c9b0 100644
--- a/api/extensions/storage/aws_s3_storage.py
+++ b/api/extensions/storage/aws_s3_storage.py
@@ -83,5 +83,5 @@ class AwsS3Storage(BaseStorage):
         except:
             return False
 
-    def delete(self, filename):
+    def delete(self, filename: str):
         self.client.delete_object(Bucket=self.bucket_name, Key=filename)
diff --git a/api/extensions/storage/azure_blob_storage.py b/api/extensions/storage/azure_blob_storage.py
index 4bccaf13c8..f270267ce9 100644
--- a/api/extensions/storage/azure_blob_storage.py
+++ b/api/extensions/storage/azure_blob_storage.py
@@ -75,7 +75,7 @@ class AzureBlobStorage(BaseStorage):
         blob = client.get_blob_client(container=self.bucket_name, blob=filename)
         return blob.exists()
 
-    def delete(self, filename):
+    def delete(self, filename: str):
         if not self.bucket_name:
             return
 
diff --git a/api/extensions/storage/baidu_obs_storage.py b/api/extensions/storage/baidu_obs_storage.py
index 0bb4648c0a..65345b0e4b 100644
--- a/api/extensions/storage/baidu_obs_storage.py
+++ b/api/extensions/storage/baidu_obs_storage.py
@@ -53,5 +53,5 @@ class BaiduObsStorage(BaseStorage):
             return False
         return True
 
-    def delete(self, filename):
+    def delete(self, filename: str):
         self.client.delete_object(bucket_name=self.bucket_name, key=filename)
diff --git a/api/extensions/storage/base_storage.py b/api/extensions/storage/base_storage.py
index 8ddedb24ae..b987c7d253 100644
--- a/api/extensions/storage/base_storage.py
+++ b/api/extensions/storage/base_storage.py
@@ -28,7 +28,7 @@ class BaseStorage(ABC):
         raise NotImplementedError
 
     @abstractmethod
-    def delete(self, filename):
+    def delete(self, filename: str):
         raise NotImplementedError
 
     def scan(self, path, files=True, directories=False) -> list[str]:
diff --git a/api/extensions/storage/google_cloud_storage.py b/api/extensions/storage/google_cloud_storage.py
index 7f59252f2f..4ad7e2d159 100644
--- a/api/extensions/storage/google_cloud_storage.py
+++ b/api/extensions/storage/google_cloud_storage.py
@@ -61,6 +61,6 @@ class GoogleCloudStorage(BaseStorage):
         blob = bucket.blob(filename)
         return blob.exists()
 
-    def delete(self, filename):
+    def delete(self, filename: str):
         bucket = self.client.get_bucket(self.bucket_name)
         bucket.delete_blob(filename)
diff --git a/api/extensions/storage/huawei_obs_storage.py b/api/extensions/storage/huawei_obs_storage.py
index 72cb59abbe..2e4961bcd5 100644
--- a/api/extensions/storage/huawei_obs_storage.py
+++ b/api/extensions/storage/huawei_obs_storage.py
@@ -41,7 +41,7 @@ class HuaweiObsStorage(BaseStorage):
             return False
         return True
 
-    def delete(self, filename):
+    def delete(self, filename: str):
         self.client.deleteObject(bucketName=self.bucket_name, objectKey=filename)
 
     def _get_meta(self, filename):
diff --git a/api/extensions/storage/oracle_oci_storage.py b/api/extensions/storage/oracle_oci_storage.py
index c032803045..c7217874e6 100644
--- a/api/extensions/storage/oracle_oci_storage.py
+++ b/api/extensions/storage/oracle_oci_storage.py
@@ -55,5 +55,5 @@ class OracleOCIStorage(BaseStorage):
         except:
             return False
 
-    def delete(self, filename):
+    def delete(self, filename: str):
         self.client.delete_object(Bucket=self.bucket_name, Key=filename)
diff --git a/api/extensions/storage/supabase_storage.py b/api/extensions/storage/supabase_storage.py
index 2ca84d4c15..76066e12f5 100644
--- a/api/extensions/storage/supabase_storage.py
+++ b/api/extensions/storage/supabase_storage.py
@@ -51,7 +51,7 @@ class SupabaseStorage(BaseStorage):
             return True
         return False
 
-    def delete(self, filename):
+    def delete(self, filename: str):
         self.client.storage.from_(self.bucket_name).remove([filename])
 
     def bucket_exists(self):
diff --git a/api/extensions/storage/tencent_cos_storage.py b/api/extensions/storage/tencent_cos_storage.py
index cf092c6973..c886c82038 100644
--- a/api/extensions/storage/tencent_cos_storage.py
+++ b/api/extensions/storage/tencent_cos_storage.py
@@ -47,5 +47,5 @@ class TencentCosStorage(BaseStorage):
     def exists(self, filename):
         return self.client.object_exists(Bucket=self.bucket_name, Key=filename)
 
-    def delete(self, filename):
+    def delete(self, filename: str):
         self.client.delete_object(Bucket=self.bucket_name, Key=filename)
diff --git a/api/extensions/storage/volcengine_tos_storage.py b/api/extensions/storage/volcengine_tos_storage.py
index a44959221f..d19d6b3032 100644
--- a/api/extensions/storage/volcengine_tos_storage.py
+++ b/api/extensions/storage/volcengine_tos_storage.py
@@ -60,7 +60,7 @@ class VolcengineTosStorage(BaseStorage):
             return False
         return True
 
-    def delete(self, filename):
+    def delete(self, filename: str):
         if not self.bucket_name:
             return
         self.client.delete_object(bucket=self.bucket_name, key=filename)
diff --git a/api/pyproject.toml b/api/pyproject.toml
index 904c4c9ca9..24569504cc 100644
--- a/api/pyproject.toml
+++ b/api/pyproject.toml
@@ -176,6 +176,7 @@ dev = [
     "sseclient-py>=1.8.0",
     "pytest-timeout>=2.4.0",
     "pytest-xdist>=3.8.0",
+    "pyrefly>=0.54.0",
 ]
 
 ############################################################
diff --git a/api/uv.lock b/api/uv.lock
index 605c62552f..3adfbecaa0 100644
--- a/api/uv.lock
+++ b/api/uv.lock
@@ -1471,6 +1471,7 @@ dev = [
     { name = "lxml-stubs" },
     { name = "mypy" },
     { name = "pandas-stubs" },
+    { name = "pyrefly" },
     { name = "pytest" },
     { name = "pytest-benchmark" },
     { name = "pytest-cov" },
@@ -1671,6 +1672,7 @@ dev = [
     { name = "lxml-stubs", specifier = "~=0.5.1" },
     { name = "mypy", specifier = "~=1.17.1" },
     { name = "pandas-stubs", specifier = "~=2.2.3" },
+    { name = "pyrefly", specifier = ">=0.54.0" },
     { name = "pytest", specifier = "~=8.3.2" },
     { name = "pytest-benchmark", specifier = "~=4.0.0" },
     { name = "pytest-cov", specifier = "~=4.1.0" },
@@ -5107,6 +5109,22 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/5a/dc/491b7661614ab97483abf2056be1deee4dc2490ecbf7bff9ab5cdbac86e1/pyreadline3-3.5.4-py3-none-any.whl", hash = "sha256:eaf8e6cc3c49bcccf145fc6067ba8643d1df34d604a1ec0eccbf7a18e6d3fae6", size = 83178, upload-time = "2024-09-19T02:40:08.598Z" },
 ]
 
+[[package]]
+name = "pyrefly"
+version = "0.54.0"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/81/44/c10b16a302fda90d0af1328f880b232761b510eab546616a7be2fdf35a57/pyrefly-0.54.0.tar.gz", hash = "sha256:c6663be64d492f0d2f2a411ada9f28a6792163d34133639378b7f3dd9a8dca94", size = 5098893, upload-time = "2026-02-23T15:44:35.111Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/5f/99/8fdcdb4e55f0227fdd9f6abce36b619bab1ecb0662b83b66adc8cba3c788/pyrefly-0.54.0-py3-none-macosx_10_12_x86_64.whl", hash = "sha256:58a3f092b6dc25ef79b2dc6c69a40f36784ca157c312bfc0baea463926a9db6d", size = 12223973, upload-time = "2026-02-23T15:44:14.278Z" },
+    { url = "https://files.pythonhosted.org/packages/90/35/c2aaf87a76003ad27b286594d2e5178f811eaa15bfe3d98dba2b47d56dd1/pyrefly-0.54.0-py3-none-macosx_11_0_arm64.whl", hash = "sha256:615081414106dd95873bc39c3a4bed68754c6cc24a8177ac51d22f88f88d3eb3", size = 11785585, upload-time = "2026-02-23T15:44:17.468Z" },
+    { url = "https://files.pythonhosted.org/packages/c4/4a/ced02691ed67e5a897714979196f08ad279ec7ec7f63c45e00a75a7f3c0e/pyrefly-0.54.0-py3-none-manylinux_2_17_aarch64.manylinux2014_aarch64.whl", hash = "sha256:0cbcaf20f5fe585079079a95205c1f3cd4542d17228cdf1df560288880623b70", size = 33381977, upload-time = "2026-02-23T15:44:19.736Z" },
+    { url = "https://files.pythonhosted.org/packages/0b/ce/72a117ed437c8f6950862181014b41e36f3c3997580e29b772b71e78d587/pyrefly-0.54.0-py3-none-manylinux_2_17_i686.manylinux2014_i686.whl", hash = "sha256:66d5da116c0d34acfbd66663addd3ca8aa78a636f6692a66e078126d3620a883", size = 35962821, upload-time = "2026-02-23T15:44:22.357Z" },
+    { url = "https://files.pythonhosted.org/packages/85/de/89013f5ae0a35d2b6b01274a92a35ee91431ea001050edf0a16748d39875/pyrefly-0.54.0-py3-none-manylinux_2_17_x86_64.manylinux2014_x86_64.whl", hash = "sha256:6ef3ac27f1a4baaf67aead64287d3163350844794aca6315ad1a9650b16ec26a", size = 38496689, upload-time = "2026-02-23T15:44:25.236Z" },
+    { url = "https://files.pythonhosted.org/packages/9f/9a/33b097c7bf498b924742dca32dd5d9c6a3fa6c2b52b63a58eb9e1980ca89/pyrefly-0.54.0-py3-none-win32.whl", hash = "sha256:7d607d72200a8afbd2db10bfefb40160a7a5d709d207161c21649cedd5cfc09a", size = 11295268, upload-time = "2026-02-23T15:44:27.551Z" },
+    { url = "https://files.pythonhosted.org/packages/d4/21/9263fd1144d2a3d7342b474f183f7785b3358a1565c864089b780110b933/pyrefly-0.54.0-py3-none-win_amd64.whl", hash = "sha256:fd416f04f89309385696f685bd5c9141011f18c8072f84d31ca20c748546e791", size = 12081810, upload-time = "2026-02-23T15:44:29.461Z" },
+    { url = "https://files.pythonhosted.org/packages/ea/5b/fad062a196c064cbc8564de5b2f4d3cb6315f852e3b31e8a1ce74c69a1ea/pyrefly-0.54.0-py3-none-win_arm64.whl", hash = "sha256:f06ab371356c7b1925e0bffe193b738797e71e5dbbff7fb5a13f90ee7521211d", size = 11564930, upload-time = "2026-02-23T15:44:33.053Z" },
+]
+
 [[package]]
 name = "pytest"
 version = "8.3.5"