Research: expand hook lifecycle to support v1 worker–evaluator dialogue and v2 mechanical lints

[samkeen]

Why

Today's hook surface is narrow: tilth/hooks/ has pre_tool and post_edit, wired through a hand-rolled tools/__init__.py:dispatch(). The contract is "success silent, failures verbose — to the agent" (see docs/deep-dives/).

This issue is the research artifact for whether the hook surface should grow into a more general lifecycle system — no code changes proposed here.

The motivation is two upcoming workstreams:

1. v1 worker–evaluator dialogue (proposals/v1-worker-evaluator-dialogue.md) introduces several natural new lifecycle points:
   • pre_submit_case — schema-validate the worker's structured case
   • pre_evaluator — assemble the ledger excerpt, gate on validator pass
   • post_evaluator — append the verdict to the per-task ledger, emit evaluator_verdict event
   • pre_halt — check halt eligibility (≥3 similar rejections, or work_arounds claims a seed contradiction)
2. v2 richer mechanical checks — Tilth's analog of OpenAI's custom lints inject remediation into agent context. That pattern is exactly "policy at well-defined event points" — which is what a lifecycle is for.

The question to answer

Does the v1+v2 set of new seams cluster into a general lifecycle system worth formalizing (event names, registry, ordering, error propagation), or is each one-off enough that ad-hoc wiring in dispatch()-style helpers stays simpler?

Premature lifecycle is its own complexity sink. The defensible answer is probably "not v1 — formalize alongside v2 custom lints, once we've actually shipped the seams and can see whether they cluster."

Scope of this issue

• Survey the v1 + v2 new event points.
• Sketch what a general lifecycle would look like (event taxonomy, registry, contract).
• Decide whether to formalize now, alongside v2, or never.

What this is not

• Not an implementation issue. No tilth/hooks/ changes proposed here.
• Not a competing design to the v1 dialogue. The v1 sketch ships on the existing narrow hook surface.

Related

• proposals/v1-worker-evaluator-dialogue.md — the dialogue proposal that exposed the question
• docs/deep-dives/ — current hook contract