The is_new branch of routedSaveClicked in editor.js used to alert on
409 and force the user to manually pick a different filename. Restore
the overwrite / keep-both / cancel prompt the legacy openEditorTextNew
flow had (via askConflict, lost when Step 9 deleted legacySaveClicked).
Flow on 409:
* "overwrite" → re-POST /save with the same path. /save overwrites
in place when the destination is a regular file.
* "keep-both" → compose a suffixed path via fo.withCollisionSuffix
(now multi-extension-aware after F3) and POST that.
* "cancel" → leave the routed modal open with the user's typed
content intact so they can edit the filename and retry.
Defensively gates the askConflict + withCollisionSuffix calls on
typeof === "function" so older bookmarks (or a dev environment with
one of the modules missing) fall back to an alert rather than a
TypeError. The 409 alert branch is preserved for that path.
Note on when /save actually 409s: regular-file collisions overwrite
silently (200). 409 fires only when the new path collides with a
directory (or a symlink, or a non-file fs entry) — same contract as
the legacy flow had.
Verified live on /overlays/2 in Chromium with a real round-trip:
1. Click "+ new folder" → create tmp_409_probe
2. Click "+ new file" → type "tmp_409_probe" → click Create
3. /save returns 409 (destination is not a file) → askConflict
opens with the colliding path displayed
4. Routed modal stays open behind the conflict dialog (typed
content preserved)
5. Cancel on conflict → conflict closes, routed modal still open
6. Cleanup: delete the tmp_409_probe folder via the action API
* No console errors throughout
* Demo overlay state unchanged after cleanup
pytest stays at 577 passed, 1 skipped, 3 deselected (no Python
changes in F4).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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