rule: verify-existing-substrate-before-authoring — sibling to dep-pin-search-first-authority (3-anchor empirical evidence 2026-05-26)

[AceHack]

Summary

Lands .claude/rules/verify-existing-substrate-before-authoring.md as the substrate-authoring-scope sibling to .claude/rules/dep-pin-search-first-authority.md (landed earlier today via PR #5126).

Empirically grounded in 3 same-root-cause failures from session 2026-05-26:

• Anchor 1: cascade Round 28 — FsCheck LawRunner (Option B) + round-29 CI anchor #4 ISO audit asserted training-data-default boot/grub/grub.cfg path (NixOS actually uses isolinux + refind). Blocked 4 ISO builds. Fixed via PR fix(ci P0): cascade #4 audit blocking ALL ISO builds since #5119 — bootloader any-of #5125. Covered by dep-pin-search-first-authority.md.
• Anchor 2: B-0806 Ace section authored without reading docs/agendas/ace-package-manager/AGENDA.md + project memory + 7+ related backlog rows. The maintainer 2026-05-26: "that is what ace has been since we first talked about it you just keep forgetting we have substantial backlog around this". Fixed via PR fix(B-0806): substrate-honest correction — Ace agenda already encodes 'package manager of package managers'; B-0806 sits INSIDE Ace not parallel to it #5130.
• Anchor 3: B-0806 hat/fork-negotiation NOT integrated into architecture even after Anchor 2 correction. The maintainer 2026-05-26: "i'm assuming you have the hat / fork negoation for ace too". Fixed via PR fix(B-0806): substrate-honest correction — Ace agenda already encodes 'package manager of package managers'; B-0806 sits INSIDE Ace not parallel to it #5130 follow-on commit.

Same root cause class, different surface

All 3 anchors are "Otto-defaults-to-plausible-but-unverified" — at different surfaces:

• Version pins / path assertions → covered by dep-pin-search-first-authority.md
• NEW substrate authoring (backlog rows, rules, skills, agenda entries, architectural framings) → covered by THIS rule
• Existing-rule citation as alibi for action → covered by fighting-past-self-vs-peer-agent-distinguisher-fix-your-own-coordinate-on-peers-dont-punt-by-default.md

Together the 3 rules cover the surfaces today's empirical evidence shows are vulnerable.

Operational discipline (per the rule body)

4-step pass before authoring new substrate:

1. Grep across substrate surfaces (agendas + trajectories + backlog + rules + memory + research)
2. READ THE TOP HITS (not just list them)
3. Decide: existing-covers / partial / no-existing
4. Cite the search inline in the new substrate

Auto-loads at cold-boot per wake-time-substrate.

Test plan

• Single rule file added; no other surface modified
• Cross-references to dep-pin + fighting-past-self + skill-router + grep-substrate-anchors compose cleanly
• 3 empirical anchors preserved with verbatim maintainer quotes

🤖 Generated with Claude Code

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Pull request overview

Adds a new .claude/rules/ wake-time substrate rule that formalizes a “search and read existing substrate before authoring new substrate” discipline, positioned as the substrate-authoring counterpart to dep-pin-search-first-authority.md.

Changes:

• Introduces verify-existing-substrate-before-authoring.md with a required pre-authoring inventory/search process and an inline checklist template.
• Captures three empirical anchors from 2026-05-26 to justify the rule and keep the motivating evidence present at cold-boot.
• Cross-references existing related rules to clarify composition across surfaces (dep pins, rule-citation failures, substrate authoring).