Spanda

Debugging Spanda in VS Code

Step through behavior, task every, and top-level every trigger loops with the Spanda debug adapter (spanda-dap) and the VS Code extension.

Prerequisites

cargo build -p spanda-dap -p spanda-cli --release
export PATH="$PWD/target/release:$PATH"

Install the Spanda VS Code extension (marketplace or local VSIX).

Launch configuration

The extension contributes a Spanda debug type. Default launch.json entry:

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "spanda",
      "request": "launch",
      "name": "Spanda: Debug current file",
      "program": "${file}"
    }
  ]
}

Workflow (killer demo)

1. Open examples/showcase/killer_demo.sd
2. Set a breakpoint inside behavior patrol() or task control_loop
3. Press F5 (Start Debugging)
4. Use Step Over (next) to advance through task every 50ms / loop every 100ms iterations
5. Inspect locals in the Variables panel when paused

CLI equivalent (breakpoint smoke test):

spanda debug examples/showcase/killer_demo.sd --break 60

What works

Capability	Status
Breakpoints on line numbers	Supported
Step over (next)	Advances periodic tasks, loop bodies, and every trigger ticks
Step in / step out	Experimental
Variables / locals	Per-frame snapshot at pause
task every loops	Step over pauses between task ticks when breakpoints hit
every trigger bodies	Debug session enters from behavior, task, or every trigger body (Phase 35)

Troubleshooting

Issue	Fix
spanda-dap not found	Build spanda-dap; set spanda.cliPath to target/release/spanda
No pause on task every	Set breakpoint inside task body; use Step Over after first hit
LSP works but debug fails	Debug uses spanda-dap, separate from LSP

Related

• killer-demo.md — flagship program for demos
• editor/vscode/README.md — extension install
• crates/spanda-dap/ — DAP server source

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