DX: Pipeline YAML Validation inline from TUI

[alexhraber]

Problem

The Buildkite CLI can validate pipeline YAML files (bk pipeline validate), but builddeck provides no way to quickly check if a .buildkite/pipeline.yml is valid. Users who edit their pipeline config have to switch to the CLI or push and wait for Buildkite to reject it.

Proposed Feature

Add a pipeline validation action accessible from the pipelines list pane. When a pipeline is highlighted, pressing a key (e.g. v) reads the local .buildkite/pipeline.yml (if one exists relative to CWD or the repo root) and validates it against the Buildkite API.

UX

1. Focus left pane (pipelines list)
2. Highlight a pipeline
3. Press v
4. If .buildkite/pipeline.yml is found:
   • Reads file content
   • Sends to Buildkite validation endpoint
   • Shows result in status bar: "Pipeline valid ✓" or inline errors
5. If no local pipeline file found:
   • Status bar shows: "No .buildkite/pipeline.yml found in repo root"

Inline Error Display for Validation Failures

Status: Pipeline validation failed:
  - Step ":test": command field is required
  - Step ":deploy": depends_on references unknown step "lint"

Why this fits a TUI

• Pipeline validation is a quick check you do while iterating on CI config
• The TUI already lists your pipelines — validating the config for the current pipeline is one key away
• Faster than bk pipeline validate because the TUI already knows your org and pipeline context

References

• bk pipeline validate in buildkite/cli
• Buildkite REST API: GET /v2/organizations/{org}/pipelines/{pipeline}/validate

Acceptance

• v key on a selected pipeline triggers validation
• Auto-discovers .buildkite/pipeline.yml from CWD or repo root
• POSTs content to Buildkite validation endpoint
• Shows "valid" or detailed error messages in status bar
• Handles "no pipeline file found" gracefully
• Loading state while API processes
• Also works from the builds pane (validates the pipeline of the selected build)

Future

• Watch mode: V (shift) watches the file for changes and re-validates on save