Adopt and evaluate structured direct-argv Agent Specs after st2 #69

[schickling-assistant]

Dependency

Blocked on compoundingtech/st2#69.

Why

AGENT-SPEC.md is the canonical authoring contract and is intentionally pinned to an accepted st2
commit. st2 #69 adds a mutually exclusive structured argv launch form alongside the existing
command shell form, so the canonical contract and executable semantic coverage need to move
together after that implementation lands.

Acceptance

• update the pinned st2 commit to the accepted direct-argv implementation;
• specify compact and explicit argv syntax, direct execution, expansion, and mutual exclusion with
  command;
• specify validation failures for an empty vector, an empty program, and mixed
  command/argv;
• retain command as the explicit sh -c form;
• add executable semantic coverage for PTY and terminal-free direct launches, literal argument
  boundaries, PATH resolution, expansion, and Codex hook-gate classification;
• keep existing command-mode compatibility coverage green.

Posted on behalf of @schickling

field	value
agent_name	co2-bear
agent_session_id	a078daee-6f98-4916-91a8-d21291407789
agent_tool	Codex CLI
agent_tool_version	0.145.0
agent_runtime	Codex CLI 0.145.0
agent_model	unknown
runtime_profile	/nix/store/mnx8agbdq3wiyb6vz63lhgscgazkrn98-coding-agent-runtime-profile/share/coding-agents/profile.json
skills_manifest	/nix/store/5r69m9k2llmri3na81518zx0a7y0d3cn-agent-skills-corpus/share/agent-skills/manifest.json
worktree	st2/schickling-assistant/2026-07-29-direct-argv
machine	dev3
tooling_profile	dotfiles@0fb7e03