diff --git a/aider/coders/patch_flex_coder.py b/aider/coders/patch_flex_coder.py
new file mode 100644
index 000000000..d68d65590
--- /dev/null
+++ b/aider/coders/patch_flex_coder.py
@@ -0,0 +1,565 @@
+# At the top of the file, add necessary imports
+import itertools
+import pathlib
+from dataclasses import dataclass, field
+from enum import Enum
+from typing import Dict, List, Optional, Tuple
+
+# Keep existing imports like dump, Coder, PatchPrompts, DiffError, ActionType
+from ..dump import dump  # noqa: F401
+from .base_coder import Coder
+from .patch_prompts import PatchPrompts
+
+
+# Import search_replace utilities
+from .search_replace import editblock_strategies, flexible_search_and_replace
+
+# Remove original Chunk, PatchAction, EditResult, Patch dataclasses if they exist at the top
+# Remove helper functions: _norm, find_context_core, find_context, peek_next_section, identify_files_needed
+# We will redefine or replace these as needed.
+
+
+# --------------------------------------------------------------------------- #
+#  Domain objects & Exceptions (Adapted for Flex Coder)
+# --------------------------------------------------------------------------- #
+class DiffError(ValueError):
+    """Any problem detected while parsing or applying a patch."""
+
+
+class ActionType(str, Enum):
+    ADD = "Add"
+    DELETE = "Delete"
+    UPDATE = "Update"
+
+
+@dataclass
+class ParsedEdit:
+    """Represents a single parsed action or change hunk."""
+
+    path: str
+    type: ActionType
+    # For UPDATE hunks:
+    search_text: Optional[str] = None
+    replace_text: Optional[str] = None
+    # For ADD:
+    new_content: Optional[str] = None
+    # For UPDATE (last hunk wins if multiple):
+    move_path: Optional[str] = None
+    # Original line number in the patch file where this hunk started (for error reporting)
+    patch_line_num: int = 0
+
+
+# --------------------------------------------------------------------------- #
+#  Helper functions (Adapted for Flex Coder)
+# --------------------------------------------------------------------------- #
+def _norm(line: str) -> str:
+    """Strip CR so comparisons work for both LF and CRLF input."""
+    return line.rstrip("\r")
+
+
+def identify_files_needed(text: str) -> List[str]:
+    """Extracts file paths from Update and Delete actions."""
+    lines = text.splitlines()
+    paths = set()
+    for line in lines:
+        norm_line = _norm(line)
+        if norm_line.startswith("*** Update File: "):
+            paths.add(norm_line[len("*** Update File: ") :].strip())
+        elif norm_line.startswith("*** Delete File: "):
+            paths.add(norm_line[len("*** Delete File: ") :].strip())
+    return list(paths)
+
+
+def _peek_change_hunk(
+    lines: List[str], index: int
+) -> Tuple[List[str], List[str], List[str], List[str], int, bool]:
+    """
+    Parses one change hunk (context-before, deleted, inserted, context-after)
+    from an Update block.
+
+    Returns: (context_before, del_lines, ins_lines, context_after, next_index, is_eof)
+    """
+    context_before: List[str] = []
+    del_lines: List[str] = []
+    ins_lines: List[str] = []
+    context_after: List[str] = []
+
+    mode = "context_before"  # States: context_before, delete, insert, context_after
+    start_index = index
+
+    while index < len(lines):
+        line = lines[index]
+        norm_line = _norm(line)
+
+        # Check for section terminators
+        if norm_line.startswith(
+            (
+                "@@",  # Start of a new scope/hunk marker
+                "*** End Patch",
+                "*** Update File:",
+                "*** Delete File:",
+                "*** Add File:",
+                "*** End of File",
+            )
+        ):
+            break
+        if norm_line == "***":
+            break
+        if norm_line.startswith("***"):
+            raise DiffError(f"Invalid patch line found in update section: {line}")
+
+        current_line_index = index
+        index += 1
+
+        # Determine line type and content
+        line_type = "unknown"
+        line_content = ""
+        if line.startswith("+"):
+            line_type = "insert"
+            line_content = line[1:]
+        elif line.startswith("-"):
+            line_type = "delete"
+            line_content = line[1:]
+        elif line.startswith(" "):
+            line_type = "context"
+            line_content = line[1:]
+        elif line.strip() == "":
+            line_type = "context"
+            line_content = ""
+        else:
+            raise DiffError(f"Invalid line prefix in update section: {line}")
+
+        # State machine logic
+        if mode == "context_before":
+            if line_type == "context":
+                context_before.append(line_content)
+            elif line_type == "delete":
+                del_lines.append(line_content)
+                mode = "delete"
+            elif line_type == "insert":
+                # Change starts with insertion (no deletion)
+                ins_lines.append(line_content)
+                mode = "insert"
+            else:
+                # Should not happen based on checks above
+                raise DiffError(f"Unexpected line type '{line_type}' in mode '{mode}': {line}")
+
+        elif mode == "delete":
+            if line_type == "delete":
+                del_lines.append(line_content)
+            elif line_type == "insert":
+                ins_lines.append(line_content)
+                mode = "insert"
+            elif line_type == "context":
+                # Deletes finished, context after starts
+                context_after.append(line_content)
+                mode = "context_after"
+            else:
+                raise DiffError(f"Unexpected line type '{line_type}' in mode '{mode}': {line}")
+
+        elif mode == "insert":
+            if line_type == "insert":
+                ins_lines.append(line_content)
+            elif line_type == "context":
+                # Inserts finished, context after starts
+                context_after.append(line_content)
+                mode = "context_after"
+            elif line_type == "delete":
+                # This implies interleaved +/- lines which this simplified parser doesn't handle well.
+                # Treat as end of hunk? Or raise error? Let's treat as end for now.
+                index = current_line_index # Put the delete line back for the next hunk
+                break
+            else:
+                raise DiffError(f"Unexpected line type '{line_type}' in mode '{mode}': {line}")
+
+        elif mode == "context_after":
+            if line_type == "context":
+                context_after.append(line_content)
+            else:
+                # Any non-context line means this hunk's context_after is finished.
+                # Put the line back for the next hunk/parser step.
+                index = current_line_index
+                break
+
+    # Check for EOF marker
+    is_eof = False
+    if index < len(lines) and _norm(lines[index]) == "*** End of File":
+        index += 1
+        is_eof = True
+
+    if index == start_index and not is_eof:
+        raise DiffError("Empty patch section found.")
+
+    # If the hunk ended immediately with context_after, the last context line
+    # might belong to the *next* hunk's context_before. This is tricky.
+    # For simplicity, we'll keep it here. flexible_search_replace might handle overlap.
+
+    return context_before, del_lines, ins_lines, context_after, index, is_eof
+
+
+# --------------------------------------------------------------------------- #
+#  PatchFlexCoder Class Implementation
+# --------------------------------------------------------------------------- #
+class PatchFlexCoder(Coder): # Rename class
+    """
+    A coder that uses the patch format for LLM output, but applies changes
+    using flexible search-and-replace logic for UPDATE actions, ignoring @@ hints
+    and precise line numbers during application.
+    """
+
+    edit_format = "patch-flex" # Give it a distinct name
+    gpt_prompts = PatchPrompts() # Use the same prompts as PatchCoder
+
+    def get_edits(self) -> List[ParsedEdit]: # Return type changed
+        """
+        Parses the LLM response content (containing the patch) into a list of
+        ParsedEdit objects, extracting search/replace blocks for UPDATEs.
+        """
+        content = self.partial_response_content
+        if not content or not content.strip():
+            return []
+
+        lines = content.splitlines()
+        start_index = 0
+        if (
+            len(lines) >= 2
+            and _norm(lines[0]).startswith("*** Begin Patch")
+        ):
+            start_index = 1
+        else:
+             # Tolerate missing sentinels if content looks like a patch action
+            is_patch_like = any(
+                _norm(line).startswith(
+                    ("@@", "*** Update File:", "*** Add File:", "*** Delete File:")
+                )
+                for line in lines
+            )
+            if not is_patch_like:
+                self.io.tool_warning("Response does not appear to be in patch format.")
+                return []
+            self.io.tool_warning(
+                "Patch format warning: Missing '*** Begin Patch' sentinel."
+            )
+
+        # Identify files needed for context lookups (only for DELETE check)
+        needed_paths = identify_files_needed(content)
+        # Unlike PatchCoder, we don't strictly need file content during parsing,
+        # but it's useful to check if DELETE targets exist.
+        # We read content dynamically in apply_edits.
+        known_files = set(self.get_inchat_relative_files()) | set(needed_paths)
+
+
+        try:
+            # Parse the patch text into ParsedEdit objects
+            parsed_edits = self._parse_patch_text(lines, start_index, known_files)
+            return parsed_edits
+        except DiffError as e:
+            raise ValueError(f"Error parsing patch content: {e}")
+        except Exception as e:
+            raise ValueError(f"Unexpected error parsing patch: {e}")
+
+    def _parse_patch_text(
+        self, lines: List[str], start_index: int, known_files: set[str]
+    ) -> List[ParsedEdit]:
+        """
+        Parses patch content lines into a list of ParsedEdit objects.
+        """
+        parsed_edits: List[ParsedEdit] = []
+        index = start_index
+        current_file_path = None
+        current_move_path = None
+
+        while index < len(lines):
+            line = lines[index]
+            norm_line = _norm(line)
+            line_num = index + 1 # 1-based for reporting
+
+            if norm_line == "*** End Patch":
+                index += 1
+                break
+
+            # ---------- UPDATE ---------- #
+            if norm_line.startswith("*** Update File: "):
+                path = norm_line[len("*** Update File: ") :].strip()
+                index += 1
+                if not path:
+                    raise DiffError(f"Update File action missing path (line {line_num}).")
+                # We don't check for duplicates here, multiple UPDATEs for the same file are handled sequentially.
+                # if path not in known_files: # Check if file is known (in chat or mentioned)
+                #     self.io.tool_warning(f"Update File target '{path}' not found in chat context.")
+
+                current_file_path = path
+                current_move_path = None # Reset move path for new file
+
+                # Check for optional Move to immediately after
+                if index < len(lines) and _norm(lines[index]).startswith("*** Move to: "):
+                    move_to = _norm(lines[index])[len("*** Move to: ") :].strip()
+                    index += 1
+                    if not move_to:
+                        raise DiffError(f"Move to action missing path (line {index}).")
+                    current_move_path = move_to
+                continue # Continue to parse hunks for this file
+
+            # ---------- DELETE ---------- #
+            elif norm_line.startswith("*** Delete File: "):
+                path = norm_line[len("*** Delete File: ") :].strip()
+                index += 1
+                if not path:
+                    raise DiffError(f"Delete File action missing path (line {line_num}).")
+                if path not in known_files:
+                     # Check against known files before adding delete action
+                    self.io.tool_warning(f"Delete File target '{path}' not found in chat context.")
+
+                parsed_edits.append(ParsedEdit(path=path, type=ActionType.DELETE, patch_line_num=line_num))
+                current_file_path = None # Reset current file context
+                current_move_path = None
+                continue
+
+            # ---------- ADD ---------- #
+            elif norm_line.startswith("*** Add File: "):
+                path = norm_line[len("*** Add File: ") :].strip()
+                index += 1
+                if not path:
+                    raise DiffError(f"Add File action missing path (line {line_num}).")
+                # if path in known_files: # Check if file might already exist
+                #     self.io.tool_warning(f"Add File target '{path}' may already exist.")
+
+                action, index = self._parse_add_file_content(lines, index)
+                action.path = path
+                action.patch_line_num = line_num
+                parsed_edits.append(action)
+                current_file_path = None # Reset current file context
+                current_move_path = None
+                continue
+
+            # ---------- Hunks within UPDATE ---------- #
+            elif current_file_path:
+                 # Skip @@ lines, they are ignored by this coder's application logic
+                if norm_line.startswith("@@"):
+                    index += 1
+                    continue
+
+                # Parse the next change hunk for the current file
+                hunk_start_index = index
+                try:
+                    (
+                        context_before,
+                        del_lines,
+                        ins_lines,
+                        context_after,
+                        next_index,
+                        _is_eof, # EOF marker not strictly needed for search/replace logic
+                    ) = _peek_change_hunk(lines, index)
+                except DiffError as e:
+                    raise DiffError(f"{e} (near line {line_num} in patch)")
+
+
+                if not del_lines and not ins_lines:
+                    # Skip hunks that contain only context - they don't represent a change
+                    index = next_index
+                    continue
+
+                # Construct search and replace text based on user request
+                # Search = context_before + deleted_lines
+                # Replace = inserted_lines + context_after
+                search_text = "\n".join(context_before + del_lines)
+                replace_text = "\n".join(ins_lines + context_after)
+
+                # Add trailing newline if original content likely had one
+                # (This helps match blocks ending at EOF)
+                # Heuristic: if context_after is empty AND there were deleted lines,
+                # the original block likely ended with the last deleted line.
+                # Or if context_before/del/ins are all empty, it's just context.
+                if not context_after and (del_lines or ins_lines):
+                     search_text += "\n"
+                     # Replace text already includes context_after, so only add if that was empty too
+                     if not ins_lines:
+                         replace_text += "\n"
+                elif context_after or context_before or del_lines or ins_lines:
+                    # If there's any content, ensure trailing newline for consistency
+                     search_text += "\n"
+                     replace_text += "\n"
+
+
+                parsed_edits.append(
+                    ParsedEdit(
+                        path=current_file_path,
+                        type=ActionType.UPDATE,
+                        search_text=search_text,
+                        replace_text=replace_text,
+                        move_path=current_move_path, # Carry over move path for this hunk
+                        patch_line_num=hunk_start_index + 1,
+                    )
+                )
+                index = next_index
+                continue
+
+            # If we are here, the line is unexpected or misplaced
+            if not norm_line.strip(): # Allow blank lines between actions/files
+                index += 1
+                continue
+
+            raise DiffError(f"Unknown or misplaced line while parsing patch (line {line_num}): {line}")
+
+        return parsed_edits
+
+    def _parse_add_file_content(self, lines: List[str], index: int) -> Tuple[ParsedEdit, int]:
+        """Parses the content (+) lines for an Add File action."""
+        added_lines: List[str] = []
+        start_line_num = index + 1
+        while index < len(lines):
+            line = lines[index]
+            norm_line = _norm(line)
+            # Stop if we hit another action or end marker
+            if norm_line.startswith(
+                (
+                    "*** End Patch",
+                    "*** Update File:",
+                    "*** Delete File:",
+                    "*** Add File:",
+                )
+            ):
+                break
+
+            if not line.startswith("+"):
+                if norm_line.strip() == "":
+                    added_lines.append("") # Treat blank line as adding a blank line
+                else:
+                    raise DiffError(f"Invalid Add File line (missing '+') (line {index+1}): {line}")
+            else:
+                added_lines.append(line[1:])
+
+            index += 1
+
+        action = ParsedEdit(
+            path="", # Path set by caller
+            type=ActionType.ADD,
+            new_content="\n".join(added_lines),
+            patch_line_num=start_line_num
+            )
+        return action, index
+
+    def apply_edits(self, edits: List[ParsedEdit]): # Argument type changed
+        """
+        Applies the parsed edits. Uses flexible search-and-replace for UPDATEs.
+        """
+        if not edits:
+            self.io.tool_output("No edits to apply.")
+            return
+
+        # Group edits by file path to process them sequentially
+        edits_by_path = itertools.groupby(edits, key=lambda edit: edit.path)
+
+        for path, path_edits_iter in edits_by_path:
+            path_edits = list(path_edits_iter)
+            full_path = self.abs_root_path(path)
+            path_obj = pathlib.Path(full_path)
+            current_content = None
+            edit_failed = False
+            final_move_path = None # Track the last move destination for this file
+
+            # Check for simple ADD/DELETE first (should ideally be only one per file)
+            if len(path_edits) == 1 and path_edits[0].type in [ActionType.ADD, ActionType.DELETE]:
+                edit = path_edits[0]
+                try:
+                    if edit.type == ActionType.ADD:
+                        if path_obj.exists():
+                             # Allow overwrite on ADD? Or error? Let's warn and overwrite.
+                            self.io.tool_warning(f"ADD Warning: File '{path}' already exists, overwriting.")
+                            # raise DiffError(f"ADD Error: File already exists: {path}")
+                        if edit.new_content is None:
+                            raise DiffError(f"ADD change for {path} has no content")
+
+                        self.io.tool_output(f"Adding {path}")
+                        path_obj.parent.mkdir(parents=True, exist_ok=True)
+                        content_to_write = edit.new_content
+                        if not content_to_write.endswith("\n"):
+                            content_to_write += "\n"
+                        self.io.write_text(full_path, content_to_write)
+
+                    elif edit.type == ActionType.DELETE:
+                        self.io.tool_output(f"Deleting {path}")
+                        if not path_obj.exists():
+                            self.io.tool_warning(f"DELETE Warning: File not found, skipping: {path}")
+                        else:
+                            path_obj.unlink()
+                except (DiffError, FileNotFoundError, IOError, OSError) as e:
+                     raise ValueError(f"Error applying action '{edit.type}' to {path}: {e}")
+                except Exception as e:
+                     raise ValueError(f"Unexpected error applying action '{edit.type}' to {path}: {e}")
+                continue # Move to the next file path
+
+            # --- Handle UPDATE actions sequentially ---
+            self.io.tool_output(f"Updating {path}...")
+            try:
+                if not path_obj.exists():
+                    raise DiffError(f"UPDATE Error: File does not exist: {path}")
+                current_content = self.io.read_text(full_path)
+                if current_content is None:
+                    raise DiffError(f"Could not read file for UPDATE: {path}")
+
+                for i, edit in enumerate(path_edits):
+                    if edit.type != ActionType.UPDATE:
+                         raise DiffError(f"Unexpected action type '{edit.type}' mixed with UPDATE for {path}")
+                    if edit.search_text is None or edit.replace_text is None:
+                         raise DiffError(f"UPDATE action for {path} is missing search/replace text")
+
+                    final_move_path = edit.move_path # Last move path specified wins
+
+                    self.io.tool_output(f"  Applying hunk {i+1} (from patch line {edit.patch_line_num})...")
+
+                    texts = (edit.search_text, edit.replace_text, current_content)
+                    new_content = flexible_search_and_replace(texts, editblock_strategies)
+
+                    if new_content is None:
+                        edit_failed = True
+                        # Provide more context on failure
+                        err_msg = (
+                            f"Failed to apply update hunk {i+1} (from patch line {edit.patch_line_num})"
+                            f" for file {path}. The search block may not have been found"
+                            " or the change conflicted.\n"
+                            f"Search block:\n```\n{edit.search_text}```\n"
+                            f"Replace block:\n```\n{edit.replace_text}```"
+                        )
+                        # Raise immediately to stop processing this file
+                        raise ValueError(err_msg)
+
+                    # Update content for the next iteration
+                    current_content = new_content
+
+                # After processing all hunks for this file:
+                if not edit_failed and current_content is not None:
+                    target_full_path = (
+                        self.abs_root_path(final_move_path) if final_move_path else full_path
+                    )
+                    target_path_obj = pathlib.Path(target_full_path)
+
+                    if final_move_path:
+                        self.io.tool_output(f"Moving updated file to {final_move_path}")
+                        if target_path_obj.exists() and full_path != target_full_path:
+                            self.io.tool_warning(
+                                "UPDATE Warning: Target file for move already exists, overwriting:"
+                                f" {final_move_path}"
+                            )
+
+                    # Ensure parent directory exists for target
+                    target_path_obj.parent.mkdir(parents=True, exist_ok=True)
+                    # Ensure trailing newline
+                    if not current_content.endswith("\n") and current_content != "":
+                         current_content += "\n"
+                    self.io.write_text(target_full_path, current_content)
+
+                    # Remove original file *after* successful write if moved
+                    if final_move_path and full_path != target_full_path:
+                        path_obj.unlink()
+
+            except (DiffError, FileNotFoundError, IOError, OSError) as e:
+                 # Raise a ValueError to signal failure
+                 raise ValueError(f"Error applying UPDATE to {path}: {e}")
+            except Exception as e:
+                 # Catch unexpected errors during application
+                 raise ValueError(f"Unexpected error applying UPDATE to {path}: {e}")
+
+    # Remove the _apply_update method as it's replaced by flexible_search_and_replace logic
+    # def _apply_update(self, text: str, action: PatchAction, path: str) -> str:
+    #    ...