A record's changed_files names the work, not the tool's exhaust

Rationale

Running Majordomus dirties the tree. majordomus update rewrites CLAUDE.md and AGENTS.md, majordomus generate rewrites share/allow/ and share/schemas/, scripts/derive rewrites docs/generated/ and site/data/generated/, and every command appends a line to the ledger. Every record this tool writes took its changed_files straight from git status --porcelain, so each one claimed all of that as the episode's work.

Measured in the Majordomus repository, where this rule was written. The record at .ai/repo/sessions/20260910T103933Z--s-20260909152316-024f--master--38f056b--… carries 122 changed files. Among them are the whole of site/data/generated/, eleven pages under site/content/sessions/, twelve files under docs/generated/ — and the three sibling records of that very episode, plus site/content/sessions/s-20260909152316-024f.md, which is that episode's own site projection. The record names itself as its own work product.

This is not cosmetic. A record is the account a later reader has of what a stretch of work contained, and the site publishes it. A list in which the signal is three real files and the noise is a hundred and nineteen is a list nobody reads, which makes the record an archive rather than a memory — exactly what majordomus.session-records exists to prevent.

Required behaviour

lib/changed.sh classifies the working tree and every record writer uses it. It carries no list of derived paths of its own. Five things already say what is derived, each maintained because something else needs it, and the classifier reads all five:

• .ai/repo/scope.yaml, out.generated.paths and out.generated.names — the tool's own declaration, shipped in the skeleton, so this works in any repository Majordomus supervises and not only in its own;
• .ai/repo/scope.yaml, out.paths — the never-read set, which is where .ai/local/ is declared. A work product nobody may read is not a work product;
• .ai/repo/policy.yaml, projections[].target — CLAUDE.md, AGENTS.md, .bb/AGENTS.md;
• .gitattributes, every path marked merge=derived — the repository's own list of what its generator writes, maintained because the merge driver needs it (in the Majordomus repository, covered by its test/cases/57_derived_merge_driver.sh);
• the record stores themselves, by the resolvers that name them. These are not derived — a closed session record is a tracked object the executable indexes — but the tool writes them and the worker does not.

A repository that declares none of them loses nothing: the classifier then excludes nothing and the list is what it was before. Adding a path to any of those declarations is what changes the outcome, which is the point — a sixth list inside the classifier would be the sixth place to forget.

Failure behaviour

Advisory, and deliberately so. Every record written before lib/changed.sh carries the unclassified list, and a record is immutable by contract: rewriting thirteen committed session records so that a check goes green would be fabricating history, which is the thing the work this rule arrived with exists to refuse. doctor reports how many records carry derived paths, which one carries the most, and which is the newest — that last number is what tells a reader whether the classifier is working, because a record written after it landed and still naming derived paths is a regression rather than a legacy.

The blocking half is the behavioural case. test/cases/136_changed_files_classifier.sh fails the build if a checkpoint, a handover or a closed session written today names a path one of the declarations covers.

Verification

mj_validate_record_changed_files in lib/changed.sh, dispatched from doctor, judges the records that exist. test/cases/136_changed_files_classifier.sh judges the writers: it sets each declaration in turn, writes one record of each kind, and asserts both halves — that the work is named and that the exhaust is not. Its last section removes a declaration and proves the path comes back, which is what shows the exclusion came from the declaration and not from a constant in the classifier.