---
id: PLN-0040
discussion: DSC-0021
decision: DEC-0019
ticket: studio-frontend-editor-write-and-save-wave
title: Implement the frontend editor write and save wave through VFS ownership
status: done
created: 2026-04-04
updated: 2026-04-04
owner: studio
tags: [studio, editor, frontend, write, save, vfs, lsp, pbs, access-policy]
---

## Briefing

Implement the accepted frontend write wave for the Studio Code Editor.
Frontend editing and frontend save must be released together, must remain owned by `prometeu-vfs`, and must be consumed by Studio UI without introducing a new immediate LSP implementation wave.

## Objective

Move frontend-scoped supported files from hard `read-only` to VFS-owned editable/saveable documents while preserving the current boundary:

- `prometeu-vfs` owns document state and persistence;
- `prometeu-lsp` remains a semantic consumer of VFS-backed snapshots;
- Studio UI remains a policy consumer.

## Dependencies

- `DEC-0019` Enable Frontend Editing and Save in the Studio Code Editor
- existing `prometeu-vfs` editable snapshot and save model for non-frontend textual documents
- existing Studio editor consumption of VFS access mode and save behavior
- existing semantic-read seam where `prometeu-lsp` reads VFS-backed frontend snapshots

## Scope

- propagate the new FE write/save contract into Studio and VFS specs
- extend `prometeu-vfs` so frontend-scoped supported files become editable/saveable
- keep FE writable snapshots, dirty tracking, and save ownership inside VFS
- update Studio editor behavior to consume FE editability from VFS
- update FE write/save tests in VFS and Studio

## Non-Goals

- any new LSP feature implementation wave
- per-file FE access policy
- partial FE draft mode without save
- moving persistence logic into Studio UI
- moving persistence logic into `prometeu-lsp`

## Execution Method

### 1. Propagate the accepted contract into specs

Update the Studio specs that still describe FE files as hard `read-only` so they now describe the new FE write/save wave and preserve VFS ownership plus semantic-consumer-only LSP ownership.

Targets:

- `docs/specs/studio/5. Code Editor Workspace Specification.md`
- `docs/specs/studio/6. Project Document VFS Specification.md`
- `docs/specs/studio/7. Integrated LSP Semantic Read Phase Specification.md`

### 2. Change FE access policy in `prometeu-vfs`

Update the filesystem-backed VFS classification so frontend-scoped supported files become `EDITABLE` rather than `READ_ONLY`, while preserving frontend classification itself.

What changes:

- document kind classification for FE files
- VFS acceptance of FE `updateDocument`
- VFS save/save-all behavior for FE snapshots
- FE dirty tracking semantics under the same VFS owner model already used for editable non-frontend documents

Targets:

- `prometeu-vfs/prometeu-vfs-v1/src/main/java/p/studio/vfs/FilesystemVfsProjectDocument.java`
- any supporting VFS API contracts if required by the implementation

Dependency ordering:

- this step must land before Studio editor UX changes so the UI can consume the new policy rather than invent it.

### 3. Update VFS tests for FE edit/save behavior

Replace tests that assert FE hard `read-only` behavior with tests that assert:

1. FE documents open as frontend documents with `EDITABLE` access mode;
2. FE documents accept `updateDocument`;
3. FE documents save correctly through `saveDocument`;
4. FE documents participate correctly in `saveAllDocuments`.

Targets:

- `prometeu-vfs/prometeu-vfs-v1/src/test/java/p/studio/vfs/FilesystemVfsProjectDocumentTest.java`

### 4. Propagate FE editability into the Studio editor

Update the Studio editor to consume the new FE access mode from VFS exactly as it already does for editable non-frontend documents.

What changes:

- FE tabs become editable when VFS reports `EDITABLE`
- FE warning surfaces that are specific to hard `read-only` FE behavior must be revised or removed
- editor save/save-all enablement must work for dirty FE buffers through the existing VFS-backed flow
- no FE-local persistence path may be introduced

Targets:

- `prometeu-studio/src/main/java/p/studio/workspaces/editor/EditorWorkspace.java`
- `prometeu-studio/src/main/java/p/studio/workspaces/editor/EditorStatusBar.java`
- any FE-warning or editor-session support classes affected by access-mode transition

Dependency ordering:

- this step depends on VFS access-mode propagation from Step 2.

### 5. Keep LSP integration stable without opening new implementation scope

Verify that the existing editor and semantic-read flow still calls `prometeu-lsp` as a consumer of FE snapshots, but do not introduce a new LSP implementation wave.

What changes:

- only compatibility adjustments that are strictly necessary because FE snapshots are now editable may be made;
- no new semantic features, refresh model, or ownership expansion is authorized here.

Targets:

- only the minimum compatibility surface if compilation or existing tests require it

Dependency ordering:

- this is verification-oriented and should follow the VFS/editor write changes.

### 6. Update Studio tests for FE editable/saveable behavior

Add or revise editor tests so they assert FE files are no longer treated as permanently hard `read-only` once VFS grants FE `EDITABLE` access mode.

Targets:

- Studio editor tests under `prometeu-studio/src/test/java/p/studio/workspaces/editor/...`
- any session/editor tests affected by FE access-mode transition

## Acceptance Criteria

1. Frontend-scoped supported files open through VFS with `EDITABLE` access mode.
2. Frontend-scoped supported files can be updated and saved through VFS-owned snapshots.
3. Studio editor FE tabs become editable only because VFS reports them as editable.
4. FE save and save-all route through the same VFS owner path used by other editable documents.
5. No new persistence or access-policy ownership moves into Studio UI.
6. No new persistence or access-policy ownership moves into `prometeu-lsp`.
7. Specs no longer describe FE files as hard `read-only` for the current wave.

## Tests

- VFS tests for FE access mode, update, save, and save-all
- Studio editor tests for FE editable/saveable behavior
- regression tests that confirm non-frontend editable documents still behave correctly
- compile/test verification that existing LSP consumer seams still pass without opening new LSP feature scope

## Affected Artifacts

- `discussion/workflow/decisions/DEC-0019-studio-frontend-editor-write-and-save-wave.md`
- `docs/specs/studio/5. Code Editor Workspace Specification.md`
- `docs/specs/studio/6. Project Document VFS Specification.md`
- `docs/specs/studio/7. Integrated LSP Semantic Read Phase Specification.md`
- `prometeu-vfs/prometeu-vfs-v1/src/main/java/p/studio/vfs/FilesystemVfsProjectDocument.java`
- `prometeu-vfs/prometeu-vfs-v1/src/test/java/p/studio/vfs/FilesystemVfsProjectDocumentTest.java`
- `prometeu-studio/src/main/java/p/studio/workspaces/editor/...`
- Studio editor tests

## Risks

- existing specs and tests currently encode the old hard `read-only` FE contract and will fail until all propagation lands coherently
- FE warning/UI surfaces may assume old read-only semantics in more than one place
- LSP snapshot consumption could reveal hidden assumptions about FE immutability even without opening a new LSP scope
- if implementation order is reversed and Studio is changed before VFS policy, UI code may drift into local heuristics