Support workflow-level tags with CEL expressions

[stack72]

Problem

There is no way to declare tags at the workflow level that automatically apply to all data artifacts produced during a workflow run. Today, if you want to tag data produced by a workflow, you must either:

1. Use --tag on the CLI at runtime (error-prone, requires discipline)
2. Add dataOutputOverrides to every step for every spec name (result, log, etc.)

For a workflow with 5 steps that each produce 2 data specs (resource + log), that's 10 dataOutputOverrides entries — all with the same tags.

Proposal

A tags field at the workflow level that supports CEL expressions and applies to all data produced during the run:

name: deploy-pipeline
inputs:
  properties:
    environment:
      type: string
      enum: [dev, staging, prod]
    image_tag:
      type: string

tags:
  environment: ${{ inputs.environment }}
  image_tag: ${{ inputs.image_tag }}

jobs:
  - name: deploy
    steps:
      - name: deploy-app
        task:
          type: model_method
          modelIdOrName: deploy-app
          methodName: execute
          inputs:
            environment: ${{ inputs.environment }}

Every data artifact produced by every step in this workflow would automatically carry environment: prod and image_tag: v1.2.3 tags (or whatever values were passed as inputs), without any per-step configuration.

Why This Matters

Multi-environment workflows are a core use case for swamp. When the same workflow runs against dev, staging, and prod, the data artifacts all land under the same model paths with incrementing version numbers. Tags are the mechanism for distinguishing which environment produced which data.

Making this automatic at the workflow level means:

• Zero boilerplate — no dataOutputOverrides on every step for every spec
• Impossible to forget — the workflow definition guarantees tagging, not the user's memory
• Self-documenting — anyone reading the workflow YAML can see exactly what metadata will be attached to the data
• Consistent — every data artifact in the run gets the same tags, including resources and logs

Use Case

A platform team maintains a library of reusable workflows (deploy, rollback, database migration, etc.). Each workflow is parameterized by environment. They need all data produced by any workflow run to be tagged with the environment, the triggering user, and the release version — without modifying every step definition in every workflow.

[github-actions]

Hi @stack72, thanks for opening this issue!

We appreciate you taking the time to report it. A maintainer will review it as soon as possible.

In the meantime, please make sure you've included all relevant details (steps to reproduce, expected vs actual behaviour, swamp version, etc.) to help us triage it quickly.

[stack72]

Closing in favor of a unified approach: adding a name field to dataOutputOverrides with CEL expression support (see #384). By varying the data name per environment (e.g., prod-result, dev-result), each environment gets its own latest symlink and distinct CEL path — eliminating the need for tag-based data isolation. Workflow-level tags may still be useful as a future nice-to-have for metadata/querying, but they're no longer needed to solve the multi-environment data problem.