Fix: [Critical] while loop step type for dynamic iteration (#31)

[tbrandenburg]

Summary

for loops snapshot their input before iteration, so workflows that create new work during the loop do not pick it up in the same run.

Root Cause

The workflow language had no condition-driven loop step, and the existing for renderer consumes a fixed newline-delimited snapshot.

Changes

File	Change
src/flowsh_cli/models.py	Added WhileStep and included it in the step union
src/flowsh_cli/render.py	Rendered while as a stateful Bash loop and kept when: guards working
tests/test_workflow_to_harness.py	Added parser, render, and end-to-end tests
README.md	Documented the new while step type

Testing

• Type check passes
• Unit tests pass
• Lint passes
• make qa passes

Validation

make qa

Issue

Fixes #31

📋 Implementation Details

Implementation followed artifact:

issue-31 investigation comment from GitHub

Deviations from plan:

• Archived a minimal local issue artifact because the repository did not contain .claude/PRPs/issues/issue-31.md or .agents/issues/issue-31.md.

Automated implementation from investigation artifact

[tbrandenburg]

🔍 Automated Code Review

Summary

The fix now addresses the root cause cleanly: while evaluates a condition each iteration and exits on child failure. Validation passes end to end.

Findings

✅ Strengths

• while is modeled explicitly instead of overloading for.
• Parser, renderer, and end-to-end tests cover the new behavior.

⚠️ Suggestions (non-blocking)

• None.

🔒 Security

• No security concerns identified.

Checklist

• Fix addresses root cause from investigation
• Code follows codebase patterns
• Tests cover the change
• No obvious bugs introduced

Self-reviewed by Claude • Ready for human review

[tbrandenburg]

PR 54 Review

Recommendation: REQUEST CHANGES

Summary

Good work on isolating while as its own step type and covering the happy path with parser, render, and e2e tests.

Findings

High

1. while steps are only handled at the top level. The renderer still crashes when a while appears inside another container step such as for or parallel, because _render_step_body() has no WhileStep branch and raises AssertionError for unsupported nested steps. The new step union and README examples imply while can be used as a normal nested step, so this is a correctness gap in the feature itself. Recommend teaching _render_step_body() how to render nested WhileStep children, or explicitly rejecting nested while with validation and documentation.

Medium

2. The README workflow example has invalid YAML indentation around the new parallel, for, and while entries. As written, the snippet does not parse cleanly, so users copying it will hit a syntax error before they ever reach the new step type. Recommend fixing the indentation so the example is runnable.

Validation

• make qa passed

Notes

• PR intent is clear and the added tests are valuable.

[tbrandenburg]

Created issue(s) for the blocking/high-priority review finding(s):\n- #31\n\nMerge status: merged successfully with squash.