I0832 — generate-site-data instrumented and its hot spots removed

Declare phases per section of the site generator, rank them, and remove the repeated work in the two most expensive sections.

DONE wave 2 · p0 · implementation profile · runs alone

Part of M004 — Performance is executable evidence, and the hot path does no canonical work twice.

Objective

Declare phases per section of the site generator, rank them, and remove the repeated work in the two most expensive sections.

Why

The generator's --check runs in CI and in case 51; it costs 27 s on this repository.

Current state

No phase inside the generator is timed.

Desired state

--check under 8 s on this repository, output byte-identical.

Scope

scripts/generate-site-data
test/cases/10_site_data.sh
test/cases/51_derived_artifacts_committed.sh

Out of scope

Changing the generated data

Dependencies

What waits on this

Acceptance criteria

Byte-identical site/data/generated before and after
The phase ranking is printed under MJ_TIMING

Validation

MJ_TIMING=1 scripts/generate-site-data --check

Evidence required

batch_reads

Evidence

covers	type	command	result	at commit
batch_reads	ci	validate run 39645593645 (attempt 2) at master 97391192dbb: suite-shard (2) job 119428809679 ran bash test/run.sh --no-skips; case 3836_a_repeated_scenario_is_read_from_its_cache ok	success	9739119

Risk

The generator shares lib/common.sh, so the flatten cache and the batch loaders apply to it directly.

Timeline

started: 2026-10-21T19:26:43Z
verified: 2026-10-21T19:27:06Z
completed: 2026-10-21T19:29:03Z

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/I0832.yaml. Read it back with majordomus plan show I0832.