Files
coder/coderd/x
Mathias Fredriksson 6b0bb02e5d fix: server-side diffs and stricter fuzzy splicing for edit_files (#24454)
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.
2026-04-18 16:39:34 +03:00
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