Add /brevity reference to each .claude/agents/ persona for sub-agent dispatch coverage

[bdchatham]

Problem

PR #89 landed the brevity skill. The Layer 2 follow-up wires it into CLAUDE.md and AGENTS.md working agreements so agents proactively apply it when authoring PR bodies + in-code comments. That catches the human-driven and council/coral-orchestrated paths.

It does NOT reliably catch sub-agent invocations dispatched via Agent tool with a specific persona (e.g., subagent_type=kubernetes-specialist). When the harness dispatches a sub-agent, it loads the persona's .claude/agents/<name>.md content into the sub-agent's context — CLAUDE.md and AGENTS.md may or may not be in scope depending on the dispatch shape and CWD.

Impact

• Today: a sub-agent asked to draft a PR body during cross-review or council synthesis may not pick up the brevity discipline because its persona file doesn't reference the skill.
• Drift: future engineers adding new agent personas will copy existing patterns, propagating the gap.
• Surface coverage: every agent in the 15-persona roster authors PR bodies at some point. The miss is universal.

Relevant experts

• product-engineer — cross-cutting; flagged this gap in PR feat(skills/brevity): discipline-enforcing brevity for PR bodies + code comments #89's layer-2 cross-review
• reviewer — convention enforcement across persona files

Proposed approach

Add a one-line reference to /brevity in each portable agent persona under .claude/agents/. Suggested placement: under the agent's existing "Boundaries" or "Working agreement" section, or as a final "Output discipline" stanza.

Concrete one-liner to standardize across personas:

Output discipline. When this persona drafts a PR body or in-code comment, it applies /brevity (.claude/skills/brevity/). The skill self-determines floor — do not pre-skip.

Apply to:

• All portable agents (sync downstream automatically via scripts/sync-agents.sh)
• Tide-specific agents (blockchain-developer, reviewer)

Skip:

• Workflow-only personas if any (none in current roster — all 15 author artifacts)

Acceptance criteria

• Every .claude/agents/*.md persona file has the output-discipline reference (or an explicit exemption with rationale)
• scripts/sync-agents.sh propagates the changes to user-scope without breakage
• Spot-check: dispatch one sub-agent (e.g., kubernetes-specialist) to draft a PR body; verify the brevity skill is referenced/applied in its output

Out of scope

• Editing the brevity skill itself
• Touching skill discovery / harness routing (separate concern)
• Persona-level changes beyond the brevity reference

References

• PR feat(skills/brevity): discipline-enforcing brevity for PR bodies + code comments #89 — landed the brevity skill
• Layer 2 PR — wires CLAUDE.md + AGENTS.md (filing alongside this issue)
• Issue Portable-scrub brevity skill + add to PORTABLE sync list #90 — portable-scrub + sync follow-up
• .claude/agents/ — the 15 persona files to touch