I2527 — An incremental derive equals a full derive byte for byte, and an omitted dependency turns a gate red

✕BLOCKED wave 5 · p1 · implementation profile · runs alone

Part of a-derive-does-only-the-work-its-inputs-changed — A derive does only the work its inputs changed, and can say why.

Objective

Hold the invariant that an incremental derive and a clean full derive of the same inputs leave the same tracked bytes, by a differential case over disposable repositories, by mutation tests that break the graph on purpose, and by a project rule with a check that runs.

Why

campaigns/majordomus-incremental-derive-prompt-pack/10_10_CORRECTNESS_ENFORCEMENT.md asks for the equivalence to be codified at the byte level, creation and deletion included, for mutation tests that omit an edge or tamper with an output and see a gate go red, and for the rules to be executable through the repository's own rule and gate owners. The incremental path fails silently in one direction: an undeclared input leaves a stale file that every key calls current. The only thing that can catch that is a comparison with the full derivation, which is why 00_00_MASTER_ORCHESTRATOR.md keeps the full derivation as the oracle.

Current state

test/cases/51_derived_artifacts_committed.sh proves a second full derive changes nothing and test/cases/400_derivation_is_one_graph.sh proves the stage order with stand-in generators. No case compares two ways of deriving, and no rule states what a derivation node owes.

Desired state

A case builds fixture repositories with stand-in producers shaped like the real graph and, for each of a no-op, a staged and an unstaged edit, a new indexed document, a renamed one, a deleted one, a changed schema, a changed executable generation, an altered output, a deleted output and an index that disagrees with the work tree, runs both paths and compares every tracked file. A crate test removes one declared edge from a copy of the graph and asserts the differential comparison fails. Rule project.incremental-derive-equals-full states: one producer per output, declared inputs complete, no cycle, no copy of the graph kept by a consumer, a reused node is not a verdict; its check is registered in .ai/repo/ci/gates.yaml.

Scope

• .ai/repo/rules/project
• .ai/repo/ci/gates.yaml
• apps/majordomus-cli/tests/derivation_differential.rs
• apps/majordomus-cli/src/derivation
• test/cases
• docs/CLAIMS.yaml
• docs/claims
• docs/DERIVE.md
• .ai/repo/project/issues/I2527.yaml

Out of scope

• Gating on a duration. Durations are recorded, and a timeout guessed from one machine is not a rule
• Regenerating golden files automatically when the comparison fails
• Running the real full derive twice inside the suite; the case uses stand-in producers, as case 400 does, and the real comparison is recorded as evidence on I2533

Dependencies

• I2525✕BLOCKED An incremental derive runs only the nodes its plan marks, a no-op derive runs no generator, and the full derive stays as it is

What waits on this

• I2529✕BLOCKED A node's outputs are kept under its key and restored only after every digest is verified
• I2532✕BLOCKED CI reuses derivation entries keyed by the graph, and still fails on a stale committed file whether or not the cache was restored
• I2533✕BLOCKED The incremental derive becomes the default after a shadow period proves it equal, and one flag returns to the full derive
• I3236✕BLOCKED Independent derive nodes run in bounded parallel against one snapshot, and the bytes do not depend on the order
• I3238✕BLOCKED A pull request runs the cases its change can affect, chosen from what each case declares it reads, and a change of unknown impact runs them all

Acceptance criteria

• For every scenario of the case, the set of tracked files and their bytes are equal after the incremental and after the full path
• With one edge removed from the graph, the case fails and names the stale file
• With an output altered and its key left alone, the incremental path regenerates it and scripts/derive-check on the altered tree exits 10
• A consumer that carries its own list of nodes or of generated paths is reported by the rule's check
• The rule is listed by majordomus rules with its enforcement declared, and the claim page names the case that proves it

Validation

• bin/majordomus plan validate
• cargo test --manifest-path apps/majordomus-cli/Cargo.toml --test derivation_differential
• MJ_TEST_JOBS=2 bash test/run.sh <the case this issue adds>
• MJ_TEST_JOBS=2 bash test/run.sh 51_derived_artifacts_committed 56_derived_current_gate
• scripts/ci-plan --check

Evidence required

• incremental_equals_full_case
• omitted_edge_turns_the_gate_red
• rule_check_registered

Evidence

None recorded. Every token above needs a command or an artifact behind it before this issue can be completed; narrative is refused.

Timeline

started

—

verified

—

completed

—

Those three fields, the evidence above and the state of the dependencies are all the status is made of. There is no status field to disagree with them.

Canonical record: .ai/repo/project/issues/I2527.yaml. Read it back with majordomus plan show I2527.