docs: add ADR-017 (track the three repo-policy rules)

docs/decisions/017-track-repo-policy-rules.md

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+---
+type: decision
+status: active
+created: 2026-06-24
+origin: code
+project: QuestionForge
+relates_to: [ADR-015, ADR-016]
+---
+
+# ADR-017: Track the three repo-policy rules in `.claude/rules/`
+
+## Context
+
+`.claude/` holds Claude Code / ACDM configuration. Historically the whole
+directory was git-ignored (`.claude/` in `.gitignore`) because most of it is
+local, path-sensitive, or personal tooling that should not travel with a clone:
+`acdm.json`, `.mcp.json`, `CLAUDE.md`, and the process rules (`acdm-workflow`,
+`tdd-required`, `escalation`, `decisions`, `language-british-english`,
+`pre-push-review`).
+
+But three of the rule files are different in kind. They are not personal
+configuration — they are **guardrails that describe the repository itself** and
+are read by repo-tooling:
+
+- `data-protection.md` — the non-negotiable "never commit personal data" rule.
+- `internal-docs-boundary.md` — what belongs in the repo vs the project's
+  internal Nextcloud documentation.
+- `publish-readiness.md` — the severity rubric and scan axes that drive the
+  `/publish-check` command.
+
+## Problem
+
+If those three rules stay git-ignored, the protections they encode exist **only
+on the original author's machine**. Anyone who clones or forks the public repo
+gets the code but not the rules that say "do not commit PII here", "this is the
+repo boundary", or "this is what publish-readiness means". The guardrail does
+not travel with the thing it guards.
+
+This is the inverse of ADR-015's principle ("flexible project init — protection
+travels with the repo"): a public repository should carry the rules that keep it
+safe, not assume every contributor reconstructs them.
+
+## Alternatives considered
+
+1. **Keep all of `.claude/` ignored (status quo).**
+   - Pro: simplest; nothing in `.claude/` is ever public by accident.
+   - Con: the PII / boundary / publish guardrails do not reach a clone or fork;
+     contributors work without the rules that protect the repo.
+
+2. **Track the whole `.claude/` directory.**
+   - Pro: everything travels.
+   - Con: publishes personal/local config (`acdm.json` paths, `.mcp.json`,
+     `CLAUDE.md`, process memos) that is path-sensitive or simply not useful to
+     outsiders — and risks leaking local paths. Fails the data-protection rule's
+     own "treat as if public" test.
+
+3. **Track only the three repo-policy rules; keep the rest ignored. (chosen)**
+   - Pro: the guardrails travel with the repo; nothing personal/local is
+     exposed. The `.gitignore` whitelist is explicit and fails closed
+     (ignore `.claude/*`, then re-include only the three named files).
+   - Con: the `.gitignore` stanza is slightly more intricate; the set of
+     "policy" vs "process" rules must be maintained deliberately.
+
+## Decision
+
+Track exactly three rule files and keep the rest of `.claude/` ignored, via an
+explicit allowlist in `.gitignore`:
+
+```gitignore
+.claude/*
+!.claude/rules/
+.claude/rules/*
+!.claude/rules/data-protection.md
+!.claude/rules/internal-docs-boundary.md
+!.claude/rules/publish-readiness.md
+```
+
+The three files were reviewed before tracking and contain **no personal data,
+no real file paths, and no secrets** — they are generic policy text using
+placeholders (`School A`, `/path/to/project`, `<Project>`). They are therefore
+safe to be public, which is a precondition for tracking them at all.
+
+A future rule only joins this set if it (a) describes the repo or is read by
+repo-tooling, and (b) passes the same "safe to be public" review.
+
+## Consequences
+
+- A clone or fork of the public repo now carries the PII-prevention rule, the
+  internal-docs boundary, and the publish-readiness rubric — the protections
+  travel with the repo.
+- Process rules, `acdm.json`, `.mcp.json`, and `CLAUDE.md` stay git-ignored.
+- `publish-readiness.md` references lessons learned from another project's
+  private→public flip by its former name; this is process "lessons learned"
+  text, not personal data, and is acceptable in a public file.
+- Adding a new rule to the tracked set is a deliberate act: extend the
+  `.gitignore` allowlist and review the file as public-safe first.