Models frequently confuse the search and replace fields in the
edit_files tool (CODAGT-312). Rename the model-facing JSON fields
to old_text/new_text so the intent is unambiguous.
Backend: custom UnmarshalJSON on editFileEdit falls back to
deprecated search/replace when old_text/new_text are empty. The
workspace agent API is unchanged; toSDKFiles maps old_text/new_text
back to search/replace for agent/agentfiles.
Frontend: normalizeEdit in parseEditFilesArgs accepts both
old_text/new_text and search/replace, normalizing to the internal
{ search, replace } representation so streaming diff rendering
works with either field naming convention.
Fixes three classes of edit_files bugs and adds structured per-file
diff output for tool callers:
- New IncludeDiff flag on FileEditRequest; when set, the agent
returns FileEditResponse.Files[]{Path, Diff} with unified diffs
computed via go-udiff v0.4.1 Lines + ToUnified (not Unified,
which calls log.Fatalf on internal error).
- Fuzzy match comparators split each line into leading whitespace,
body, trailing whitespace, and ending. The splice substitutes at
each position: on agreement between search and replace the file's
bytes win; on disagreement the replacement's bytes are spliced
verbatim. Carve-outs for empty-body lines, multi-line EOF splices,
and level-aware indent translation for inserted lines.
- Indent-unit detection (GCD for spaces, tab-priority) lets a 4sp
LLM search insert correctly into tab or 2sp files. Falls back to
the previous cLead-inheritance path when units can't be detected
cleanly.
- Empty search is rejected with "search string must not be empty".
- Duplicate file paths in one request are rejected; symlink aliases
resolved via api.resolvePath before the dedup check.
- Frontend EditFilesRenderer consumes the structured files array by
explicit path (no label munging) with per-file synthetic fallback
for older agents or mismatched paths. On error, no diff is
rendered so the synthetic fallback doesn't misrepresent a
rejected edit as applied.
Breaking change: AgentConn.EditFiles changes from (ctx, req) error
to (ctx, req) (FileEditResponse, error) in codersdk/workspacesdk.
Source-breaking for external Go consumers; no compat shim per plan
owner.
Out of scope (tracked in CODAGT-214): level-aware indent for
middle-substituted splice lines. Locked in
TestEditFiles_FuzzyIndent_InsertionLevelAware's Lock_* cases plus
TestEditFiles_ReplaceAll_FuzzyIndentGap.
> This PR was authored by Mux on behalf of Mike.
## Summary
- add persistent plan mode for chats and the chat-specific plan file
flow
- add structured planning tools such as `ask_user_question` and
`propose_plan`
- keep `write_file` and `edit_files` constrained to the chat-specific
plan file during plan turns
- allow shell exploration in plan mode, including subagents, via
`execute` and `process_output`
- block implementation-oriented, provider-native, MCP, dynamic, and
computer-use tools during plan turns
- update the chat UI, tests, and docs for the new planning flow
> This PR was authored by Mux on behalf of Mike.
Chats sharing one workspace (e.g. sibling subagents) all wrote to
`/home/coder/PLAN.md`, causing plan file collisions. This change derives
a unique plan path per chat from the workspace home directory and chat
ID.
## Changes
* `write_file`, `edit_files`, and `propose_plan` reject any `plan.md`
variant (case-insensitive) at the workspace home root, with a clear
error pointing to the chat-specific path.
* Root chats receive a `<plan-file-path>` block inlined in the main
system prompt with the concrete path.
* Prompt and tool descriptions no longer hardcode `/home/coder/PLAN.md`.
* Plan path handling is POSIX-only (forward-slash), relying on the
contract that workspace agent paths are normalized before reaching
chatd.
* Updated `ProposePlanTool.stories.tsx` to use per-chat path examples.
* Full test coverage for plan path detection, legacy-path rejection in
all three tools, inline prompt rendering, and fallback behavior.
Mathias Fredriksson