Bug

The plan node in archon-piv-loop writes the plan file to docs/plans/{slug}.plan.md instead of .claude/archon/plans/{slug}.plan.md. The downstream implement-setup bash node expects the file at .claude/archon/plans/ and fails immediately:

ERROR: No plan file found in .claude/archon/plans/

Root Cause

The workflow YAML (archon-piv-loop.yaml, around line 204) instructs the plan node to save to .claude/archon/plans/{slug}.plan.md. The AI agent executing the plan node disobeys this instruction and writes to docs/plans/{slug}.plan.md instead — likely defaulting to a more conventional project location.

This is a probabilistic LLM-instruction-following issue, but when it triggers, the downstream failure is deterministic.

Reproduction

1. Start archon-piv-loop workflow (web UI or CLI)
2. Approve the explore gate
3. Plan node runs and writes the plan file
4. implement-setup bash node fails because the plan file is not at the expected path

Not 100% reproducible — depends on whether the LLM follows the path instruction. Observed on 2026-04-22 during a full end-to-end interactive piv-loop run.

Workaround

1. Find the plan file the agent actually wrote (check docs/plans/ in the worktree or feature branch)
2. Copy it to .claude/archon/plans/{slug}.plan.md on the feature branch and push
3. Fire a fresh /workflow run archon-piv-loop .claude/archon/plans/{slug}.plan.md — passing the path argument lets Archon validate-only instead of re-planning

Proposed Fix

Two options (not mutually exclusive):

1. Harden the prompt. Add explicit path validation or a stronger instruction in the plan node's system prompt (e.g., IMPORTANT: You MUST write the plan to .claude/archon/plans/{slug}.plan.md — no other path.)

2. Fallback search in implement-setup. Have the bash node check both .claude/archon/plans/ and docs/plans/ before failing. If found in the wrong location, move it and continue.

Environment

• Archon v0.3.6
• macOS (web UI, local dev server)
• Workflow: archon-piv-loop

Claude-discovered, human-verified. Identified by Claude during an interactive piv-loop session; reproduction steps and workaround confirmed by a human operator.