GuyPaddock · GuyPaddock · Dec 17, 2025 · Dec 17, 2025 · Dec 17, 2025 · Dec 20, 2025
diff --git a/6940ed8d-87ac-8331-8c1a-653841289646.json b/6940ed8d-87ac-8331-8c1a-653841289646.json
diff --git a/config.template.toml b/config.template.toml
@@ -243,7 +243,7 @@ enable_browsing = true
 # Whether the LLM draft editor is enabled
 enable_llm_editor = false
 
-# Whether the standard editor tool (str_replace_editor) is enabled
+# Whether the standard editor tool (apply_patch) is enabled
 # Only has an effect if enable_llm_editor is False
 enable_editor = true
 

diff --git a/frontend/src/components/features/chat/event-content-helpers/get-observation-content.ts b/frontend/src/components/features/chat/event-content-helpers/get-observation-content.ts
@@ -1,4 +1,5 @@
 import {
+  ApplyPatchObservation,
   ReadObservation,
   CommandObservation,
   IPythonObservation,
@@ -12,6 +13,18 @@ import { getObservationResult } from "./get-observation-result";
 import { getDefaultEventContent, MAX_CONTENT_LENGTH } from "./shared";
 import i18n from "#/i18n";
 
+const getApplyPatchObservationContent = (event: ApplyPatchObservation): string => {
+  let contentDetails = '';
+
+  event?.extras?.applied_hunks?.forEach(({ action, file }) => {
+    contentDetails += `✔ ${action} \`${file}\`\n`;
+  });
+
+  contentDetails += `\n\`\`\`${event.extras.patch || ""}\n\`\`\``
+
+  return contentDetails;
+}
+
 const getReadObservationContent = (event: ReadObservation): string =>
   `\`\`\`\n${event.content}\n\`\`\``;
 
@@ -142,6 +155,8 @@ const getTaskTrackingObservationContent = (
 
 export const getObservationContent = (event: OpenHandsObservation): string => {
   switch (event.observation) {
+    case "apply_patch":
+      return getApplyPatchObservationContent(event);
     case "read":
       return getReadObservationContent(event);
     case "edit":

diff --git a/frontend/src/components/features/chat/event-content-helpers/get-observation-result.ts b/frontend/src/components/features/chat/event-content-helpers/get-observation-result.ts
@@ -30,6 +30,8 @@ export const getObservationResult = (event: OpenHandsObservation) => {
         return hasContent ? "success" : "error";
       }
       return hasContent ? "success" : "error";
+    case "apply_patch":
+      return "success";
     default:
       return "success";
   }

diff --git a/frontend/src/components/v1/chat/event-content-helpers/get-event-content.tsx b/frontend/src/components/v1/chat/event-content-helpers/get-event-content.tsx
@@ -48,6 +48,9 @@ const getActionEventTitle = (event: OpenHandsEvent): React.ReactNode => {
   let actionValues: Record<string, unknown> = {};
 
   switch (actionType) {
+    case "ApplyPatchAction":
+      actionKey = "ACTION_MESSAGE$APPLY_PATCH";
+      break;
     case "ExecuteBashAction":
       actionKey = "ACTION_MESSAGE$RUN";
       actionValues = {
@@ -109,6 +112,9 @@ const getObservationEventTitle = (event: OpenHandsEvent): React.ReactNode => {
   let observationValues: Record<string, unknown> = {};
 
   switch (observationType) {
+    case "ApplyPatchObservation":
+      actionKey = "OBSERVATION_MESSAGE$APPLY_PATCH";
+      break;
     case "ExecuteBashObservation":
       observationKey = "OBSERVATION_MESSAGE$RUN";
       observationValues = {

diff --git a/frontend/src/i18n/translation.json b/frontend/src/i18n/translation.json
@@ -8079,6 +8079,22 @@
     "tr": "<path>{{path}}</path> dosyasına yazılıyor",
     "uk": "Записую в <path>{{path}}</path>"
   },
+  "ACTION_MESSAGE$APPLY_PATCH": {
+    "en": "Applying patch",
+    "ja": "パッチを適用中",
+    "zh-CN": "正在应用补丁",
+    "zh-TW": "正在套用修補程式",
+    "ko-KR": "패치를 적용 중입니다",
+    "no": "Patch brukes",
+    "ar": "جارٍ تطبيق التصحيح",
+    "de": "Patch wird angewendet",
+    "fr": "Application du correctif",
+    "it": "Applicazione della patch",
+    "pt": "Aplicando correção",
+    "es": "Aplicando parche",
+    "tr": "Yama uygulanıyor",
+    "uk": "Застосовується патч"
+  },
   "ACTION_MESSAGE$BROWSE": {
     "en": "Browsing the web",
     "zh-CN": "浏览",
@@ -8255,6 +8271,22 @@
     "tr": "<path>{{path}}</path> dosyasına yazıldı",
     "uk": "Записав на <path>{{path}}</path>"
   },
+  "OBSERVATION_MESSAGE$APPLY_PATCH": {
+    "en": "Applied patch",
+    "ja": "パッチを適用しました",
+    "zh-CN": "已应用补丁",
+    "zh-TW": "已套用修補程式",
+    "ko-KR": "패치를 적용했습니다",
+    "no": "Patch ble brukt",
+    "ar": "تم تطبيق التصحيح",
+    "de": "Patch angewendet",
+    "fr": "Correctif appliqué",
+    "it": "Patch applicata",
+    "pt": "Correção aplicada",
+    "es": "Parche aplicado",
+    "tr": "Yama uygulandı",
+    "uk": "Патч застосовано"
+  },
   "OBSERVATION_MESSAGE$BROWSE": {
     "en": "Browsing completed",
     "zh-CN": "浏览",

diff --git a/frontend/src/mocks/mock-ws-helpers.ts b/frontend/src/mocks/mock-ws-helpers.ts
@@ -123,7 +123,7 @@ export const createMockAgentErrorEvent = (
   id: "error-event-123",
   timestamp: new Date().toISOString(),
   source: "agent",
-  tool_name: "str_replace_editor",
+  tool_name: "apply_patch",
   tool_call_id: "tool-call-456",
   error: "Failed to execute command: Permission denied",
   ...overrides,

diff --git a/frontend/src/types/core/base.ts b/frontend/src/types/core/base.ts
@@ -15,6 +15,8 @@ export type OpenHandsEventType =
   | "think"
   | "finish"
   | "error"
+  | "patch_error"
+  | "patch_success"
   | "recall"
   | "mcp"
   | "call_tool_mcp"

diff --git a/frontend/src/types/core/observations.ts b/frontend/src/types/core/observations.ts
@@ -103,6 +103,14 @@ export interface ErrorObservation extends OpenHandsObservationEvent<"error"> {
   };
 }
 
+export interface ApplyPatchObservation extends OpenHandsObservationEvent<"apply_patch"> {
+  source: "agent";
+  extras: {
+    patch: string;
+    applied_hunks: {};
+  };
+}
+
 export interface AgentThinkObservation
   extends OpenHandsObservationEvent<"think"> {
   source: "agent";
@@ -173,6 +181,7 @@ export type OpenHandsObservation =
   | ReadObservation
   | EditObservation
   | ErrorObservation
+  | ApplyPatchObservation
   | RecallObservation
   | MCPObservation
   | UserRejectedObservation

diff --git a/openhands/agenthub/README.md b/openhands/agenthub/README.md
@@ -75,7 +75,7 @@ Here is a list of available Observations:
 - [`FileReadObservation`](../events/observation/files.py)
 - [`FileWriteObservation`](../events/observation/files.py)
 - [`ErrorObservation`](../events/observation/error.py)
-- [`SuccessObservation`](../events/observation/success.py)
+- [`ApplyPatchObservation`](../events/observation/apply_patch.py)
 
 You can use `observation.to_dict()` and `observation_from_dict` to serialize and deserialize observations.
 

diff --git a/openhands/agenthub/codeact_agent/README.md b/openhands/agenthub/codeact_agent/README.md
@@ -11,7 +11,8 @@ The CodeAct agent operates through a function calling interface. At each turn, t
    - Execute Linux `bash` commands with `execute_bash`
    - Run Python code in an [IPython](https://ipython.org/) environment with `execute_ipython_cell`
    - Interact with web browsers using `browser` and `fetch`
-   - Edit files using `str_replace_editor` or `edit_file`
+   - Edit files using `apply_patch` or `edit_file`
+   - View files with line numbers using `view_file`
 
 ![image](https://github.com/OpenHands/OpenHands/assets/38853559/92b622e3-72ad-4a61-8f41-8c040b6d5fb3)
 
@@ -37,14 +38,16 @@ The agent provides several built-in tools:
 - Supports common browser actions like navigation, clicking, form filling, scrolling
 - Handles file uploads and drag-and-drop operations
 
-### 4. `str_replace_editor`
-- View, create and edit files through string replacement
-- Persistent state across command calls
-- File viewing with line numbers
-- String replacement with exact matching
-- Undo functionality for edits
+### 4. `view_file`
+- View files (with line numbers) or list directories
+- Supports optional line ranges
+- Works with absolute or workspace-relative paths
 
-### 5. `edit_file` (LLM-based)
+### 5. `apply_patch`
+- Atomic patch-based editing for create/update/delete
+- Structured JSON diagnostics when available
+
+### 6. `edit_file` (LLM-based)
 - Edit files using LLM-based content generation
 - Support for partial file edits with line ranges
 - Handles large files by editing specific sections

diff --git a/openhands/agenthub/codeact_agent/codeact_agent.py b/openhands/agenthub/codeact_agent/codeact_agent.py
@@ -20,13 +20,14 @@
 from openhands.agenthub.codeact_agent.tools.finish import FinishTool
 from openhands.agenthub.codeact_agent.tools.ipython import IPythonTool
 from openhands.agenthub.codeact_agent.tools.llm_based_edit import LLMBasedFileEditTool
-from openhands.agenthub.codeact_agent.tools.str_replace_editor import (
-    create_str_replace_editor_tool,
+from openhands.agenthub.codeact_agent.tools.apply_patch import (
+    create_apply_patch_tool,
 )
 from openhands.agenthub.codeact_agent.tools.task_tracker import (
     create_task_tracker_tool,
 )
 from openhands.agenthub.codeact_agent.tools.think import ThinkTool
+from openhands.agenthub.codeact_agent.tools.view import create_view_file_tool
 from openhands.controller.agent import Agent
 from openhands.controller.state.state import State
 from openhands.core.config import AgentConfig
@@ -141,15 +142,12 @@ def _get_tools(self) -> list['ChatCompletionToolParam']:
         if self.config.enable_plan_mode:
             # In plan mode, we use the task_tracker tool for task management
             tools.append(create_task_tracker_tool(use_short_tool_desc))
+        if self.config.enable_editor or self.config.enable_llm_editor:
+            tools.append(create_view_file_tool())
         if self.config.enable_llm_editor:
             tools.append(LLMBasedFileEditTool)
         elif self.config.enable_editor:
-            tools.append(
-                create_str_replace_editor_tool(
-                    use_short_description=use_short_tool_desc,
-                    runtime_type=self.config.runtime,
-                )
-            )
+            tools.append(create_apply_patch_tool())
         return tools
 
     def reset(self) -> None:

diff --git a/openhands/agenthub/codeact_agent/function_calling.py b/openhands/agenthub/codeact_agent/function_calling.py
@@ -17,7 +17,7 @@
     LLMBasedFileEditTool,
     ThinkTool,
     create_cmd_run_tool,
-    create_str_replace_editor_tool,
+    create_view_file_tool,
 )
 from openhands.agenthub.codeact_agent.tools.security_utils import RISK_LEVELS
 from openhands.core.exceptions import (
@@ -31,6 +31,7 @@
     AgentDelegateAction,
     AgentFinishAction,
     AgentThinkAction,
+    ApplyPatchAction,
     BrowseInteractiveAction,
     CmdRunAction,
     FileEditAction,
@@ -43,8 +44,7 @@
 from openhands.events.action.mcp import MCPAction
 from openhands.events.event import FileEditSource, FileReadSource
 from openhands.events.tool import ToolCallMetadata
-from openhands.llm.tool_names import TASK_TRACKER_TOOL_NAME
-
+from openhands.llm.tool_names import APPLY_PATCH_TOOL_NAME, TASK_TRACKER_TOOL_NAME
 
 def combine_thought(action: Action, thought: str) -> Action:
     if not hasattr(action, 'thought'):
@@ -170,62 +170,24 @@ def response_to_actions(
                         'impl_source', FileEditSource.LLM_BASED_EDIT
                     ),
                 )
-            elif (
-                tool_call.function.name
-                == create_str_replace_editor_tool()['function']['name']
-            ):
-                if 'command' not in arguments:
+            elif tool_call.function.name == APPLY_PATCH_TOOL_NAME:
+                if 'patch' not in arguments:
                     raise FunctionCallValidationError(
-                        f'Missing required argument "command" in tool call {tool_call.function.name}'
+                        f'Missing required argument "patch" in tool call {tool_call.function.name}'
                     )
+                action = ApplyPatchAction(patch=arguments['patch'].rstrip('\n'))
+                set_security_risk(action, arguments)
+            elif tool_call.function.name == create_view_file_tool()['function']['name']:
                 if 'path' not in arguments:
                     raise FunctionCallValidationError(
                         f'Missing required argument "path" in tool call {tool_call.function.name}'
                     )
-                path = arguments['path']
-                command = arguments['command']
-                other_kwargs = {
-                    k: v for k, v in arguments.items() if k not in ['command', 'path']
-                }
-
-                if command == 'view':
-                    action = FileReadAction(
-                        path=path,
-                        impl_source=FileReadSource.OH_ACI,
-                        view_range=other_kwargs.get('view_range', None),
-                    )
-                else:
-                    if 'view_range' in other_kwargs:
-                        # Remove view_range from other_kwargs since it is not needed for FileEditAction
-                        other_kwargs.pop('view_range')
-
-                    # Filter out unexpected arguments
-                    valid_kwargs_for_editor = {}
-                    # Get valid parameters from the str_replace_editor tool definition
-                    str_replace_editor_tool = create_str_replace_editor_tool()
-                    valid_params = set(
-                        str_replace_editor_tool['function']['parameters'][
-                            'properties'
-                        ].keys()
-                    )
-
-                    for key, value in other_kwargs.items():
-                        if key in valid_params:
-                            # security_risk is valid but should NOT be part of editor kwargs
-                            if key != 'security_risk':
-                                valid_kwargs_for_editor[key] = value
-                        else:
-                            raise FunctionCallValidationError(
-                                f'Unexpected argument {key} in tool call {tool_call.function.name}. Allowed arguments are: {valid_params}'
-                            )
-
-                    action = FileEditAction(
-                        path=path,
-                        command=command,
-                        impl_source=FileEditSource.OH_ACI,
-                        **valid_kwargs_for_editor,
-                    )
 
+                action = FileReadAction(
+                    path=arguments['path'],
+                    impl_source=FileReadSource.OH_ACI,
+                    view_range=arguments.get('view_range'),
+                )
                 set_security_risk(action, arguments)
             # ================================================
             # AgentThinkAction