Self-host M2: Close spine coverage gap (603→606 inventory units)

[PurHur]

Problem

compiler_lib_spine_smoke links 603 require_once units; Phase A inventory reports 606 files on the bin/vm.php path (php script/bootstrap-inventory.php --check). #1922 and #2001 closed earlier spine batches; #1955 flipped SELFHOST_SPINE_COVERAGE_SYNC_GATE=1 default-on — the checker will fail until the last 3 inventory paths are in the spine bundle (or documented substitutes).

Without a focused tracker, M2 work scatters across #1492 / #1768 instead of a finish-line checklist.

Goal

php script/check-selfhost-spine-coverage-sync.php   # exit 0
BOOTSTRAP_LIB_SPINE_SMOKE=1 make bootstrap-selfhost-lib-spine-smoke   # native link OK
php script/bootstrap-spine-count.php                # spine == inventory coverage

Scope

1. Identify the 3 missing inventory paths via check-selfhost-spine-coverage-sync.php --verbose
2. Add require_once to test/selfhost/compiler_lib_spine_smoke/main.php (or extend spineSubstitutes / deferred tables in the checker with linked issues if link-blocked)
3. Fix any native link/JIT stubs uncovered by new units (may touch Self-host M3: compile-driver real lowering symbol batch tracker #1768 symbol batches)
4. Update docs/bootstrap-selfhost.md M2 row to 606/606

Implementation hints

Step	Command / file
Gap list	php script/check-selfhost-spine-coverage-sync.php --verbose
Spine main	test/selfhost/compiler_lib_spine_smoke/main.php
Substitutes	script/check-selfhost-spine-coverage-sync.php $spineSubstitutes, $deferred
Count SSOT	script/bootstrap-spine-count.php
Native link	script/bootstrap-selfhost-lib-spine-smoke.sh

Acceptance criteria

docker run --rm -v "$(pwd):/compiler" -w /compiler php-compiler:22.04-dev \
  php script/check-selfhost-spine-coverage-sync.php
docker run --rm -v "$(pwd):/compiler" -w /compiler php-compiler:22.04-dev \
  env BOOTSTRAP_LIB_SPINE_SMOKE=1 ./script/bootstrap-selfhost-lib-spine-smoke.sh

No GitHub Actions required.

Dependencies

• Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 epic · Self-host M3: compile-driver real lowering symbol batch tracker #1768 if new units need compile-driver symbols
• Blocks honest M3/M4 claims on full inventory coverage

Links

• ROADMAP 🗺️ ROADMAP: Self-host + web-capable PHP subset (living) #78 Phase 5 Self-host · closed Self-host M2: Close compiler_lib_spine_smoke gap (589→593 inventory units) #1922, Self-host M2: Re-add 6 spine units trimmed in #1988 (Linker, vm_run_smoke, …) #2001, CI: Default SELFHOST_SPINE_COVERAGE_SYNC_GATE=1 in ci-fast after #1922 spine gap closed #1955

[PurHur]

Superseded scope (batch 113): The 603→606 gap from batch 110/112 is largely closed on master (spine smoke links; coverage checker passes with documented deferred paths).

New gap: bootstrap-inventory.php regen reports 611 files vs 606 spine require_once units — track finish-line work in #2066 (inventory 606→611 + #1802 footnotes). Link PRs there; keep this issue for historical 603→606 context only.

php script/bootstrap-inventory.php --check
php script/check-selfhost-spine-coverage-sync.php --verbose
php script/check-wave3-roadmap-sync.php

[PurHur]

Superseded (batch 114): 603→606 scope from this issue is closed on master. Active spine gap is 606→611 — track in #2066 only.

Do not file new “603 vs 606” issues; run:

php script/bootstrap-inventory.php --check
php script/check-selfhost-spine-coverage-sync.php
php script/check-wave3-roadmap-sync.php