docs(AGENTS): add quality-steward row + cross-repo scope note

[melon-claw]

Summary

• Adds quality-steward row to the Agent team table in ingest AGENTS.md, pointing at the sibling-owned cfo persona (no local duplicate persona file).
• Adds a short note clarifying that quality-steward reaches across both repos but the milestone-close retro step isn't mirrored on the ingest side (ingest doesn't have independent milestones today).

Context

Surfaced during the refresh of the cfo-side control-room issue (cfo#1). A pulse-check against both repos flagged:

• cfo AGENTS.md and cfo .claude/agents/quality-steward.md both assert the steward covers both repos from a single trigger ("Covers both cfo and ingest from a single trigger" — verbatim).
• ingest AGENTS.md Agent team table listed only code-reviewer, cloud-ops-specialist, simplify — silent on quality-steward.
• quality-steward: paused label exists in this repo (kill switch operational); the cfo-side ADR-0011 is the governance anchor.

The scope claim is therefore real on the cfo side but invisible to a fresh ingest-side agent. This PR fixes the drift with a single table row plus one explanatory paragraph.

What this is not

• Not a sentinel-parity fix. The cfo-side gate (SHA-anchored CHANGES REQUESTED, reviewed-sha: binding, scripts/check_reviewer_verdict.py) and the ingest-side gate (regex over REQUEST_CHANGES|CHANGES_REQUESTED, created_at latest-wins, no SHA binding) have diverged in both docs and implementation. That's a structural decision — filed separately, linked below when the issue lands.
• Not a persona-file duplication. The cfo persona states it covers both repos; mirroring the file here would be a second source of truth to drift. The row references the sibling file directly.

Test plan

• AGENTS.md table row added, consistent column widths preserved (visual diff).
• Links resolve: cfo persona, cfo ADR-0011, cfo#111 (QS scheduled task), ingest#10 (companion).
• No persona files added; no scripts touched; no code paths changed.

🤖 Generated with Claude Code

[melon-claw]

[code-reviewer] verdict: APPROVED
reviewed-sha: 0e1fbab

Summary

Docs-only change. One table row + one explanatory paragraph added to ingest AGENTS.md. All five review axes checked: truthfulness, link correctness, table consistency, scope hygiene, and broader correctness. No blocking issues found.

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Truthfulness

Every claim in the new row was verified against the cfo persona and the cfo AGENTS.md table row.

• "Covers both cfo and ingest from a single trigger — files separate issues per repo" — exact match with the persona's description block ("Covers both melon-monarch-cfo and melon-monarch-ingest from a single trigger") and the cfo table row ("Covers both cfo and ingest from a single trigger").
• "Periodic retrospection + proactive quality/architecture improvement" — verbatim from both the persona frontmatter description and the cfo table row.
• Kill switch label: row says quality-steward: paused — confirmed to exist in this repo via gh label list.
• "60-day backstop" — correct; the persona says "default proposal: 60-day backstop if no milestone closes."
• Scheduled-task wiring on cfo#111 — issue exists, open, title is "Wire quality-steward scheduled task (every 60 days, cfo+ingest scope)". Accurate.
• Companion issue [META] Periodic retrospection + quality steward — ingest companion #10 — exists, open, title is "[META] Periodic retrospection + quality steward — ingest companion". Accurate.

One minor observation, not a blocker: the cfo AGENTS.md table row also names "Drafts milestone retros" as part of the Owns column. The ingest row omits this, which is defensible since the paragraph below correctly explains that milestone-close retro ritual is not adopted on the ingest side. The omission is honest rather than inconsistent.

Link correctness

All four absolute GitHub URLs resolve:

• https://github.com/melon-lab-com/melon-monarch-cfo/blob/main/.claude/agents/quality-steward.md — file confirmed via GitHub API.
• https://github.com/melon-lab-com/melon-monarch-cfo/blob/main/docs/decisions/0011-retro-and-quality-steward.md — file confirmed via GitHub API.
• https://github.com/melon-lab-com/melon-monarch-cfo/issues/111 — issue open.
• https://github.com/melon-lab-com/melon-monarch-ingest/issues/10 — issue open.

Table style consistency

The new row follows the same column-width padding convention as the two existing custom-persona rows (code-reviewer, cloud-ops-specialist). The File cell uses the "sibling-owned — see [...]" pattern rather than a local relative link, which is appropriate and self-explanatory. No style drift.

Scope hygiene

The paragraph is honest on three counts:

1. "No local persona file in this repo" — correct; no .claude/agents/quality-steward.md exists in ingest.
2. "Retro at milestone close is not yet adopted" with the correct reason ("ingest doesn't have independent milestones today") — accurate and appropriately narrow. Does not over-promise or create a false gate.
3. "Pulse-check and persona-health audits cover this repo regardless" — consistent with the persona's explicit scope ("You are the quality-steward for melon-monarch-cfo and melon-monarch-ingest").

On sentinel/parity drift: the paragraph correctly acknowledges the asymmetry without implying it needs to be fixed in this PR. The persona itself treats the milestone-retro gate as cfo-only in practice (the hard gate language applies where milestones exist), so leaving the asymmetry documented but unresolved is the right call here. No scope creep; nothing implied that needs a companion fix.

No other concerns

No dead links, no fabricated claims, no scope leakage, no missing coverage for the change itself.