Oxygen for Visual Studio Code

1. Goals

1. Parity with the built-in Git extension. Everything a VS Code user does with Git through the UI must be doable with Oxygen through the UI: see what changed, diff it, commit some or all of it, switch bookmarks, sync with a remote, see history, resolve conflicts, and get gutter and explorer decorations, without opening a terminal.
2. Expose what Oxygen does better. Exact blame, first-class conflicts with a resolution flow, undo of any operation, bisect, subrepositories, and the trust policy get first-class UI rather than being hidden behind the Git vocabulary.
3. Never lie about state. The extension shows what oxy reports and nothing it infers; every mutation goes through oxy, so the operation log stays the single source of truth and oxy undo works on what the extension did.
4. Fast enough to run on every keystroke pause. Status refresh after a file save must complete within the manifest stat-cache budget (tens of milliseconds on a warm repository, spec §12.4).

Non-goals for 1.0: a web UI, code review, issue tracking (those belong to oxyhub), a Git compatibility mode (the built-in Git extension already covers Git repositories), and remote development on a machine without oxy.

2. How it compares

3. Architecture

• Language and build. TypeScript, bundled with esbuild, targeting the current VS Code engine. Tests with @vscode/test-electron against a fixture repository created with oxy in a temporary directory.
• Process model. The extension spawns oxy per operation with --plain --json (§4) and parses its output; it never reads .oxy/ itself. Long operations (clone, push, fetch, bisect run) stream progress to a VS Code progress notification and can be cancelled by killing the process. One operation mutates a repository at a time; reads may run concurrently.
• Repository model. One Repository object per workspace folder containing (or nested under) an oxy repository, found with oxy root (§4). It holds the last status --json, bookmark list --json, and prompt results, and refreshes on: a file watcher over the workspace (debounced 250 ms, ignoring .oxy/), a watcher on .oxy/ops/head (any operation, including ones from a terminal), window focus, and after every command the extension runs itself.
• Binary discovery. oxygen.path setting, else oxy on PATH, else ~/.local/bin/oxy. The extension checks oxy --version at activation and shows a one-click "Install or locate oxy" message if it is missing or older than the minimum it supports.
• URIs. oxy: URIs serve file content from a state: oxy:/<path>?change=<hash>&repo=<root>; change may be @base (the working copy's base), a ChangeHash, a ChangeId prefix, or a bookmark. A TextDocumentContentProvider answers them with oxy cat.
• Activation. On workspaceContains:.oxy and on the oxygen.* commands.

4. Machine interface required from oxy

The extension depends on stable JSON outputs. These are additions to the reference implementation, tracked as phase 3 in oxygen/docs/plan.md:

Every JSON command MUST print one JSON document on stdout and nothing else, use exit status 0 for success, and put human-readable errors on stderr with a non-zero status. Ids are hex strings. Times are milliseconds since the epoch.

5. User interface

5.1 Source Control view

• Groups: Conflicts (only when present, listed first), Changes. Each entry shows the path, a status letter, and a tooltip with the status word; clicking opens the diff editor (working file against oxy: base content; for an added file the file itself; for a removed file the base content).
• Title actions: Commit (with message box), Refresh, Fetch, Pull, Push, More… (Amend, Undo last operation, Open history, Open operation log).
• Entry actions: Open file, Open changes, Discard changes (confirm), Commit only this path.
• Multi-select commit: selecting entries and choosing "Commit selected" runs oxy commit PATH...
• The view's badge is the number of changed paths; the badge turns red with the conflict count while conflicts exist.

5.2 Diff editor and quick diff

• Quick diff decorations in the gutter come from the base content served over oxy:.
• The diff editor title is path (base ↔ working copy); for history diffs, path (change A ↔ change B).
• "Commit this hunk" and "Discard this hunk" CodeLens actions in the diff editor call oxy commit --hunks and oxy discard --hunks (the latter is a phase 3 addition to oxy).

5.3 Commit

• The message box supports multi-line messages; Ctrl+Enter commits everything, the dropdown offers Commit selected paths, Commit hunks… (opens a quick pick of hunks from oxy hunks --json), Amend, Amend into… (quick pick of changes), and Commit and push.
• Empty message: the extension opens an editor for the message, like Git's.
• A pre-commit hook veto shows its stderr in a notification with "Show output".

5.4 Status bar

• Left: ⚛ main 658990aa ✎ from oxy prompt --glyphs, coloured by state; click opens the bookmark picker.
• Next to it: ↑2 ↓1 sync counts; click runs Sync (fetch then pull then push, each confirmed on first use).
• A spinner while any command runs; conflicts show ‼ 2 in the warning colour; click opens the Conflicts group.

5.5 Bookmarks

• Picker: current bookmark marked, each with heads count and ahead/behind, plus Create bookmark…, Merge bookmark into current…, Delete bookmark…. Switching with uncommitted changes offers Discard or Cancel (never silently).
• Explorer context menu on a folder: "Open in new workspace" runs oxy workspace add.

5.6 History view

• A webview showing the bookmark's changes as a graph: nodes are changes, edges are dependencies, heads highlighted, the working copy at the top. Multiple heads render side by side with no fake merge nodes.
• Clicking a change opens its summary (message, author, files, signature); actions: checkout, describe, abandon, squash into…, rebase onto…, tag, blame this version of a file, open diff against parent.
• Filters: bookmark, author, path, text.

5.7 Conflicts

• Files with markers open in the editor with CodeLens over each region: Accept side 1, Accept side 2, Accept both, Compare sides. Side labels are the contributing changes' short ids and subjects, as the markers carry them.
• Tree conflicts (.oxy-conflict-N candidates) appear under Conflicts with actions "Keep this candidate" (renames it into place and removes the rest).
• "Mark resolved" runs oxy resolve --json and reports what remains; the commit action reads "Commit resolution" while conflicts are resolved but not committed.

5.8 Blame

• Command "Toggle inline blame" decorates each line's end with changeid · author · age; hovering shows the full message with a link to the change. A "Blame" side view lists the same per line. Uses oxy blame --json on the base content and adjusts for unsaved edits by dimming lines that differ from base.

5.9 Operation log

• A tree view listing operations newest first with time and command; each has Undo to here. The item corresponding to the current view is marked. Snapshot operations are hidden by default.

5.10 Subrepositories

• A Subrepos node in the SCM view when .oxymodules exists or subrepo nodes are tracked: each entry shows path, pin, and state (at pin, differs, dirty, missing) with actions Update, Update all (--init), Open folder.

5.11 Bisect

• Panel with Start, Good/Bad marking of the state under test, Run with a task or command, Skip, Reset, and a progress line ("7 candidates, about 3 steps"). The culprit opens in the history view.

5.12 Trust

• Each change in the history view shows a signature badge (signed, sealed, unsigned, invalid, revoked key). A Trust section in the SCM view summarises the policy (roots, rules, expiry) and flags an expired policy or an unverified remote.

5.13 Remotes and sync

• Remote picker for fetch/pull/push when more than one remote exists; results shown as notifications (rejected pushes explain why and offer Pull). Tokens are read from the repository configuration; the extension never stores secrets itself.

5.14 Settings

5.15 Commands (all prefixed Oxygen:)

Commit, Commit Selected Paths, Commit Hunks…, Amend, Amend Into…, Discard Changes, Refresh, Fetch, Pull, Push, Push Bookmark…, Sync, Switch Bookmark…, Create Bookmark…, Merge Bookmark…, Delete Bookmark…, Open History, Open Operation Log, Undo Last Operation, Toggle Inline Blame, Show Blame, Resolve Conflicts, Mark Resolved, Checkout Change…, Describe Change…, Abandon Change…, Squash Into…, Rebase Onto…, Create Tag…, Add Workspace…, Update Subrepos, Bisect Start/Good/Bad/Skip/Run/Reset, Verify Signatures, Show Policy, Open Output, Clone Repository…, Initialize Repository.

Keybindings match the Git extension where a counterpart exists (for example Ctrl+Enter in the commit box).

6. Behaviour rules

• Refresh is cheap and debounced; a refresh never blocks the UI thread and never runs two status calls at once per repository.
• Errors from oxy appear verbatim in a notification with "Show output"; the output channel logs every command, its working directory, duration, and exit status.
• Nothing destructive without a confirmation: discard, delete bookmark, abandon, --discard switches, and force push all confirm, with a "Don't ask again" option per action.
• Multi-root workspaces: one repository model per folder; the SCM view shows a provider per repository, as Git does.
• Files outside the sparse filter are shown greyed with a tooltip.
• Large repositories: history and blame are paged (-n) and fetched on demand; decorations use status --json only.

7. Repository layout and tooling

oxygen-vscode/
  package.json          contributes: commands, views, menus, keybindings, settings, scm
  src/
    extension.ts        activation, repository discovery
    oxy.ts              process wrapper and JSON parsing (one function per §4 command)
    model/              Repository, status, bookmarks, operations
    scm/                SourceControl provider and resource groups
    views/              history (webview), operation log, blame, subrepos, bisect, trust
    editor/             oxy: content provider, quick diff, conflict CodeLens, inline blame
    commands/           one file per command group
  assets/images/        oxygen.svg (the extension icon), history webview assets
  test/                 integration tests against a fixture repository
  docs/spec.md          this document

Build with npm run build (esbuild), test with npm test, package with vsce package, publish to the Marketplace under the oxygen publisher once 1.0 is reached. CI runs lint, build, and tests on Linux, macOS, and Windows with a pinned oxy release.

8. Milestones

1. 0.1 Read-only: activation, binary discovery, SCM view with Changes and Conflicts, diff editor over oxy:, quick diff, decorations, status bar. Requires oxy root, cat, status --json (exists), prompt.
2. 0.2 Write: commit (all, paths, hunks, amend), discard, refresh on operations, undo, operation log view. Requires hunks --json, commit --hunks, discard, op log --json.
3. 0.3 Bookmarks and sync: picker, create/switch/merge/delete, fetch/pull/push with results, remotes. Requires bookmark list --json, sync --json outputs.
4. 0.4 History and blame: history webview, timeline, inline blame, show. Requires log --json, show --json, diff --json.
5. 0.5 Conflicts: conflict editor CodeLens, tree conflict candidates, resolve flow. Requires resolve --json.
6. 0.6 The rest: subrepos, bisect, trust, tags, workspaces, clone and init.
7. 1.0: tests on three platforms, Marketplace listing, documentation.

8a. Implementation notes (2026-09-27)

• The Timeline API is still proposed in VS Code, so file history is a command with a quick pick and diffs between versions rather than a Timeline provider.
• oxy gained tag list --json and workspace list --json for §4, and two bugs the extension's tests found were fixed in oxy: a chosen addition hunk now carries its content, and an unsigned repository keeps a tag's message.
• Extensions are per VS Code profile; the install command must name the profile a workspace uses.

9a. Exported API (0.7.0)

activate returns an OxygenAPI (src/api.ts): the repositories as handles (root, status, bookmarks, current bookmark, remotes(), json(args), refresh()), onDidChangeStatus, onDidChangeRepositories, getRepository(path), and registerRemoteProvider. A remote provider gives an id and label, matches(remoteUrl) and urlFor(remoteUrl, target) for repository, bookmark, change, file (with line), proposals and issues targets. This extension uses the providers for its Open on Remote commands and sets the oxygen.hasRemoteProvider context; oxygenhub-vscode registers one for hubs and consumes the handles instead of running oxy itself, mirroring how the GitHub Pull Requests extension builds on the built-in Git extension.

9. Open questions

1. Whether the extension should ship oxy binaries for the three platforms or only locate one; shipping simplifies onboarding but ties releases together.
2. Whether inline blame should run on every edit (as GitLens does) or only on save; the stat cache makes per-save cheap, per-edit needs a content-aware diff against base in the extension.
3. Whether a long-lived oxy daemon (oxy serve-ide) is warranted for very large repositories, where spawning a process per refresh would dominate.