CI: COMPILER_DRIVER_SMOKE_GATE opt-in in ci-local after compiler_driver native probe

[PurHur]

Problem

#2136 ✅ landed compiler_driver_smoke native link+execute (script/bootstrap-selfhost-compiler-driver-smoke-link.sh, BootstrapCompilerDriverSmokeTest). ci-local.sh already calls ci_run_bootstrap_compiler_driver_smoke() when COMPILER_DRIVER_SMOKE_GATE=1, but the gate defaults to 0 — contributors must opt in manually.

Default flip is tracked in #2168 (after this opt-in gate is green one release).

Goal

1. Document opt-in path clearly (this issue = docs + harness verify)
2. COMPILER_DRIVER_SMOKE_GATE=1 workflow stable on Runforge/Docker
3. CI: Default COMPILER_DRIVER_SMOKE_GATE=1 in ci-local after #2137 opt-in green #2168 — separate issue for ci-defaults.env default-on

Implementation hints

Piece	Path	Notes
Env	script/ci-defaults.env	COMPILER_DRIVER_SMOKE_GATE="${COMPILER_DRIVER_SMOKE_GATE:-0}" (already present)
Hook	script/ci-common.sh	ci_run_bootstrap_compiler_driver_smoke() — skip when LLVM missing
Entry	script/ci-local.sh	llvm tail after lib-spine-vm-smoke
Probe	script/bootstrap-selfhost-compiler-driver-smoke-link.sh	Native link + run; stdout compiler_driver_smoke bundle OK
Fixture	test/selfhost/compiler_driver_smoke/main.php	M3 driver bundle
PHPUnit	test/unit/BootstrapCompilerDriverSmokeTest.php	@group llvm
Docs	docs/local-ci-matrix.md, docs/bootstrap-selfhost.md	Gate row + harness commands
Doctor	lib/Doctor.php --selfhost	Mention opt-in flag

COMPILER_DRIVER_SMOKE_GATE=1 ./script/ci-local.sh
# targeted:
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh && COMPILER_DRIVER_SMOKE_GATE=1 vendor/bin/phpunit --group llvm --filter BootstrapCompilerDriverSmokeTest'

Acceptance criteria

• Opt-in gate documented in docs/local-ci-matrix.md with harness snippet (no raw docker run -v)
• COMPILER_DRIVER_SMOKE_GATE=1 ./script/ci-local.sh passes on harness when LLVM 9 present
• Skip message when LLVM missing (same as other @group llvm gates)
• CI: Default COMPILER_DRIVER_SMOKE_GATE=1 in ci-local after #2137 opt-in green #2168 filed/linked for default-on flip (do not change default in this issue)
• No GitHub Actions

Dependencies

• Self-host M3: compiler_driver_smoke native link + execute probe #2136 ✅ — probe script + test
• Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492 — M3 spine epic
• CI: Default COMPILER_DRIVER_SMOKE_GATE=1 in ci-local after #2137 opt-in green #2168 — default-on follow-up (sibling; not duplicate)

Links

• ROADMAP 🗺️ ROADMAP: Self-host + web-capable PHP subset (living) #78 · Self-host M3: native compile-driver probe on lib/Compiler.php unit #2216 Compiler.php unit probe (parallel M3 track)
• Local CI canonical: Test Compiling Speed #436 / Disable github actions for now #394 (not GHA)

Verification

make docker-build-22   # once
COMPILER_DRIVER_SMOKE_GATE=1 ./script/docker-ci-local.sh

[PurHur]

Gate ladder de-dupe (batch 131): Opt-in wiring only — default-on flip is #2168.

Step	Issue	Env	CI entry
1	#2136 ✅	—	compiler_driver_smoke probe script
2	#2137 (this)	COMPILER_DRIVER_SMOKE_GATE=1	ci-local.sh llvm group opt-in
3	#2168	default :=1 in ci-defaults.env	after one harness release green

Not GHA (#47 ✅ / #394 ✅). Verify:

COMPILER_DRIVER_SMOKE_GATE=1 ./script/docker-ci-local.sh

Sibling: #1968 → #2165 (M3 compile-smoke strict) uses the same opt-in → default-on pattern.

[PurHur]

De-dupe (batch 132): gate ladder with #2168 — local CI only

This issue is the opt-in step; #2168 is the default-on flip after this gate is green on harness. Do not open a third issue for the same env var.

Stage	Issue	Env
Probe green	#2136 ✅	compiler_driver_smoke native link+run
ci-local opt-in	#2137 (here)	COMPILER_DRIVER_SMOKE_GATE=1
ci-local default	#2168	flip :-1 in ci-defaults.env

Verify: ./script/ci-local.sh or ./script/docker-ci-local.sh — not GHA (#47 ✅ / #394 ✅).

LLVM: toolchain upgrade is #174 only — not a CI policy issue.

[PurHur]

Gate ladder (batch 133): Opt-in #2137 (COMPILER_DRIVER_SMOKE_GATE) must land before default flip #2168. Depends on #2136 ✅ native probe. Parallel M2 track: #2134 → #2201 VM driver execute. No GHA — wire in script/ci-local.sh llvm group only.

[PurHur]

Backlog de-dupe (batch 134): Opt-in gate for compiler_driver_smoke native link+run (#2136 ✅). Default-on flip: #2168 — implement #2137 first, then #2168 only after one release green on php-compiler:22.04-dev.

Verify: COMPILER_DRIVER_SMOKE_GATE=1 ./script/ci-local.sh or make test-harness.

[PurHur]

De-dupe (batch 135): Opt-in (#2137) ↔ default-on flip (#2168) — same COMPILER_DRIVER_SMOKE_GATE env. Parent probe #2136 ✅. Wire opt-in first; flip only after harness ci-local llvm tail green. Not related to #174 (LLVM version) or GHA (#394).

[PurHur]

Backlog de-dupe (batch 136): Opt-in COMPILER_DRIVER_SMOKE_GATE=1 (this issue). Default-on flip is #2168 only — do not duplicate. Probe landed #2136 ✅. Expanded body batch 136.

[PurHur]

Closing as superseded by #2168 ✅: COMPILER_DRIVER_SMOKE_GATE defaults to 1 in script/ci-defaults.env (#2136 probe + #2168 flip). Opt-out =0 documented in docs/local-ci-matrix.md. Do not reopen for merge gates — use make test-harness / ./script/docker-ci-local.sh.