feat: add retry-with-exponential-backoff plugin

.secrets.baseline

@@ -3,7 +3,7 @@
     "files": "package-lock.json|Cargo.lock|^.secrets.baseline$|scripts/sign_image.sh|scripts/zap|sonar-project.properties|^/Users/brian/dev/github.ibm.com/contextforge-org/sps-pipeline-config/.secrets.baseline$|^./.secrets.baseline$",
     "lines": null
   },
-  "generated_at": "2026-03-27T22:09:20Z",
+  "generated_at": "2026-03-28T14:11:28Z",
   "plugins_used": [
     {
       "name": "AWSKeyDetector"
@@ -10080,87 +10080,87 @@
         "hashed_secret": "d63b39580934e062f89aae63426d2f2c77c3e258",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 501,
+        "line_number": 503,
         "type": "Base64 High Entropy String",
         "verified_result": null
       },
       {
         "hashed_secret": "586a55a9b8b97f0cd88e24ce8279ebc955949688",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 502,
+        "line_number": 504,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "00cafd126182e8a9e7c01bb2f0dfd00496be724f",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 518,
+        "line_number": 520,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "7b1552c7c7ffb8bd70b5666e5997c8e017630aab",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 1936,
+        "line_number": 1934,
         "type": "Base64 High Entropy String",
         "verified_result": null
       },
       {
         "hashed_secret": "9fb7fe1217aed442b04c0f5e43b5d5a7d3287097",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 2704,
+        "line_number": 2702,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "72cb70dbbafe97e5ea13ad88acd65d08389439b0",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 3332,
+        "line_number": 3330,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "ee977806d7286510da8b9a7492ba58e2484c0ecc",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 5366,
+        "line_number": 5609,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "f2e7745f43b0ef0e2c2faf61d6c6a28be2965750",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 5858,
+        "line_number": 6101,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "4a249743d4d2241bd2ae085b4fe654d089488295",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 7025,
+        "line_number": 7268,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "0c8d051d3c7eada5d31b53d9936fce6bcc232ae2",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 7163,
+        "line_number": 7406,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "f2b14f68eb995facb3a1c35287b778d5bd785511",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 7492,
+        "line_number": 7735,
         "type": "Secret Keyword",
         "verified_result": null
       }
@@ -10202,55 +10202,55 @@
         "hashed_secret": "99834bc4eff3f1e1c1e4692d2476b593b501d045",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 5481,
+        "line_number": 5483,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "f2b14f68eb995facb3a1c35287b778d5bd785511",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 5499,
+        "line_number": 5501,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "b8cec023ad982a1355abb9e7c7700e42d7e6fac3",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 5523,
+        "line_number": 5525,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "0614eb27c6e0d2f4ed9a1cce2a5bcbbbc17aa556",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 5587,
+        "line_number": 5589,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "a38fea79a043f0c9a62f851659d459dc3b716ea9",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 5598,
+        "line_number": 5600,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "a50da1fb101595ac5158f2c9394a65a84061b56c",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 5639,
+        "line_number": 5641,
         "type": "Secret Keyword",
         "verified_result": null
       },
       {
         "hashed_secret": "ed3e0017cb8e4b06a59af1a441f62cbe58d2ef59",
         "is_secret": false,
         "is_verified": false,
-        "line_number": 5645,
+        "line_number": 5647,
         "type": "Secret Keyword",
         "verified_result": null
       }

mcpgateway/plugins/framework/manager.py

@@ -170,6 +170,7 @@ async def execute(
         combined_metadata: dict[str, Any] = {}
         current_payload: PluginPayload | None = None
         decision_plugin_name: Optional[str] = None
+        max_retry_delay_ms: int = 0
 
         for hook_ref in hook_refs:
             # Skip disabled plugins
@@ -224,6 +225,9 @@ async def execute(
                 combined_metadata,
             )
 
+            # Propagate retry signal — take the largest delay requested by any plugin
+            max_retry_delay_ms = max(max_retry_delay_ms, result.retry_delay_ms)
+
             # Apply policy-based controlled merge (per-plugin)
             if result.modified_payload is not None:
                 if policy:
@@ -292,7 +296,7 @@ async def execute(
         if hook_type == HTTP_AUTH_CHECK_PERMISSION_HOOK and decision_plugin_name:
             combined_metadata[DECISION_PLUGIN_METADATA_KEY] = decision_plugin_name
 
-        return (PluginResult(continue_processing=True, modified_payload=current_payload, violation=None, metadata=combined_metadata), res_local_contexts)
+        return (PluginResult(continue_processing=True, modified_payload=current_payload, violation=None, metadata=combined_metadata, retry_delay_ms=max_retry_delay_ms), res_local_contexts)
 
     async def execute_plugin(
         self,

mcpgateway/plugins/framework/models.py

@@ -1336,6 +1336,9 @@ class PluginResult(BaseModel, Generic[T]):
             violation (Optional[PluginViolation]): violation object.
             metadata (Optional[dict[str, Any]]): additional metadata.
             http_headers (Optional[dict[str, str]]): HTTP headers to include in successful responses.
+            retry_delay_ms (int): Milliseconds the gateway should wait before retrying the tool call.
+                0 (default) means no retry. Set by retry_with_backoff plugin to request
+                a delayed re-execution of the tool.
 
      Examples:
         >>> result = PluginResult()
@@ -1358,13 +1361,17 @@ class PluginResult(BaseModel, Generic[T]):
         >>> r2 = PluginResult(continue_processing=False)
         >>> r2.continue_processing
         False
+        >>> r3 = PluginResult(retry_delay_ms=500)
+        >>> r3.retry_delay_ms
+        500
     """
 
     continue_processing: bool = True
     modified_payload: Optional[T] = None
     violation: Optional[PluginViolation] = None
     metadata: Optional[dict[str, Any]] = Field(default_factory=dict)
     http_headers: Optional[dict[str, str]] = None
+    retry_delay_ms: int = 0
 
 
 class GlobalContext(BaseModel):