Fallout Build View (PoC)

Proof-of-concept VS Code extension that renders the Fallout build's target graph as a tree view — a structured alternative to the Mermaid HTML produced by --plan.

How it works

The framework side ships an experimental graph export (BuildGraphUtility, diagnostic ID FALLOUT001): every time a Fallout build starts from its project, EmitBuildGraphAttribute writes .fallout/temp/build-graph.json containing every target with its description, default flag, and all three dependency kinds (dependsOn = execution, after = order, triggeredBy/triggers = trigger). This extension just reads that file.

The tree shows each target at the root (default target gets a rocket icon, unlisted targets are dimmed at the bottom); expanding a target reveals its related targets labeled by relation kind, recursively. A file watcher refreshes the view whenever the JSON is rewritten — i.e. on every build run.

Besides the tree, Fallout: Show Build Graph (title-bar icon on the view) opens a webview panel that renders the whole graph with Mermaid (bundled locally — webviews have no network), themed for VS Code light/dark. Solid edges = execution dependencies, dashed = order, thick = triggers; the default target gets a bold border, unlisted targets are dimmed. Clicking a node runs that target. The panel re-renders automatically when build-graph.json changes, so it supersedes the browser-based --plan HTML.

Commands:

• inline ▶ on a tree item — runs that target via ./build.ps1 <Target> (or build.sh) in a Fallout terminal
• right-click a tree item → Go to Definition — jumps to the Target <Name> => declaration in the C# source. Resolves via the C# language service first, falling back to a regex scan over workspace .cs files; the declaredIn field in build-graph.json (the declaring type, e.g. a component interface like ICompile) disambiguates same-named targets. Multiple surviving candidates open a quick pick.
• Fallout: Show Build Graph — Mermaid graph in a webview panel, click a node to run it
• Fallout: Refresh Targets — re-reads the JSON
• Fallout: Show Execution Plan (legacy HTML) — runs --plan for the classic browser view (overflow menu)

Try it

cd poc/vscode-fallout
npm install
npm run compile

Then open poc/vscode-fallout as a folder in VS Code and press F5 — the Extension Development Host opens the Fallout repo root with the Fallout Targets view in the Explorer sidebar. If the view is empty, run the build once (./build.ps1 --help is enough) to generate .fallout/temp/build-graph.json.

Known PoC limitations

• Reads the first workspace folder that has a graph file; no multi-root build support.
• The JSON only exists after one build invocation (same lifecycle as build.schema.json).
• No live build progress — the view is static structure. Streaming target status during a running build (queued/running/succeeded/failed) is the obvious next step and would need a small execution-event emitter on the framework side.
• The webview loads Mermaid from node_modules — fine under F5; packaging with vsce would need the file whitelisted (or a bundler).
• Webview node-click parsing relies on Mermaid's <prefix>-<TargetName>-<n> DOM-id scheme.

Tracked ideas

• Native task provider (vscode.tasks.registerTaskProvider) so targets appear in Tasks: Run Task with problem matchers.
• Go-to-definition could be made exact (no regex heuristics) if the framework emitted source locations into build-graph.json — e.g. captured via [CallerFilePath]/[CallerLineNumber] on the Target delegate plumbing.