fix: implement fabricates a substitute plan when plan path is missing instead of failing fast

[blafourcade]

Reported from AKEO enterprise framework feedback (training follow-up).

Description

When aidd-dev:02-implement is launched but the expected plan file is not found at the given path (e.g. the plan was written to the current branch instead of the worktree the implement runs in), the skill does not stop. It improvises a substitute plan and runs it — producing off-topic work.

Root cause, verified in the code:

• implement takes the plan via $ARGUMENTS (plugins/aidd-dev/skills/02-implement/actions/01-implement.md, input plan: <path to or content of the implementation plan>).
• There is no documented behavior when the path is missing or invalid — no fail-fast guard. The model fills the gap by fabricating a plan.
• The framework has no worktree concept (only git checkout -b), so it cannot detect "plan in the wrong branch/worktree" specifically. The correct, general guard is: plan path missing/invalid → stop. That covers the worktree case as a side effect.

Affected file(s)

plugins/aidd-dev/skills/02-implement/actions/01-implement.md

Expected behaviour

If the plan path passed to implement does not resolve to a readable plan file (and no inline plan content was provided), the skill fails fast with a clear error ("plan not found at ") and stops — it never fabricates a substitute plan.

Observed behaviour

implement proceeds, silently regenerates a substitute plan, and executes it — fully off-topic relative to the intended plan.

AI tool

Claude Code

OS

macOS

Additional context

Pairs with the brainstorm → plan persistence issue: together they harden the whole plan handoff (durable plan in, fail-fast if absent).