Part of #2172.
Context
We register hooks on SessionStart, UserPromptSubmit, PreToolUse, PostToolUse, SessionEnd, Stop and SubagentStop — but nothing on SubagentStart.
nWave uses it: a 64-line handler reads the hook input, and for nw-* agent types writes an additionalContext JSON reminder naming the skill files to load. Fail-open — any exception exits 0 so the spawned subagent is never blocked by a reminder hook.
Our equivalent is prose inside each agent body ("Cites:" lists, and in several agents an explicit instruction to read named knowledge files). That works, but it is instruction-following, and it costs the same tokens on every dispatch whether or not the agent needed reminding. A hook injects it deterministically at boot and can tailor it to the dispatched agent.
Goal
Register a SubagentStart hook that injects the dispatched agent's required context deterministically, so the agent file does not have to carry the reminder as prose.
Approach
- Read the dispatched
subagent_type; resolve its Cites: list from the agent file (the same closed registry hooks/lib/review_agent_registry already reads for agent_dispatch_ledger.py — reuse it, do not build a second source of truth).
- Emit
additionalContext naming the resolved knowledge paths.
- Fail-open, unconditionally. An exception, an unknown agent type, or an unreadable
agents/ directory exits 0 with no output. A reminder hook must never block a dispatch.
- Decide whether this replaces the prose in agent bodies or duplicates it. Replacing is the only version that saves tokens; duplicating costs more than today. If the prose stays for agents dispatched outside this plugin's hooks, say so explicitly and scope which agents rely on which mechanism.
Acceptance criteria
- A dispatch of a registered review agent receives
additionalContext listing exactly the knowledge files that agent's Cites: names.
- An unregistered or misspelled
subagent_type produces no output and exit 0.
- Malformed stdin, absent
agents/ directory, and an exception in resolution each exit 0 silently.
- If agent-body prose is removed in favor of the hook,
/agent-audit passes and agent-eval fixtures show no detection regression for at least the agents whose prose was removed — a context injection that arrives differently must not change what the agent finds.
knowledge/telemetry-schema.md updated if the hook emits any boundary event.- Full pre-push pytest directory list green.
Out of scope
- Changing what any agent cites. This slice changes the delivery mechanism, not the content.
Part of #2172.
Context
We register hooks on
SessionStart,UserPromptSubmit,PreToolUse,PostToolUse,SessionEnd,StopandSubagentStop— but nothing onSubagentStart.nWave uses it: a 64-line handler reads the hook input, and for
nw-*agent types writes anadditionalContextJSON reminder naming the skill files to load. Fail-open — any exception exits 0 so the spawned subagent is never blocked by a reminder hook.Our equivalent is prose inside each agent body ("Cites:" lists, and in several agents an explicit instruction to read named knowledge files). That works, but it is instruction-following, and it costs the same tokens on every dispatch whether or not the agent needed reminding. A hook injects it deterministically at boot and can tailor it to the dispatched agent.
Goal
Register a
SubagentStarthook that injects the dispatched agent's required context deterministically, so the agent file does not have to carry the reminder as prose.Approach
subagent_type; resolve itsCites:list from the agent file (the same closed registryhooks/lib/review_agent_registryalready reads foragent_dispatch_ledger.py— reuse it, do not build a second source of truth).additionalContextnaming the resolved knowledge paths.agents/directory exits 0 with no output. A reminder hook must never block a dispatch.Acceptance criteria
additionalContextlisting exactly the knowledge files that agent'sCites:names.subagent_typeproduces no output and exit 0.agents/directory, and an exception in resolution each exit 0 silently./agent-auditpasses andagent-evalfixtures show no detection regression for at least the agents whose prose was removed — a context injection that arrives differently must not change what the agent finds.knowledge/telemetry-schema.mdupdated if the hook emits any boundary event.Out of scope