feat(reg-vm,jit): land optimizing-JIT work + clear landing blockers

Large JIT advance on the register-VM native tier (Cranelift): OSR, scalar
replacement (Option/Result/variant/struct), closure inlining/sinking,
combinator expansion, checked-int elision, and a transactional heap-write
boundary, plus the supporting hardening harness (differential + deopt-stress
backends, perf gate, CI lanes, fuzz targets) and the reg_vm/analyzer/hir
module decomposition.

Blocker fixes (this pass, all differential-green in the dev container):
- reg-vm: CallNative added to native_jit_written_reg (stale field memoization)
- reg-vm: OSR pipeline threads the slice-elision ip-map (silent OSR bail)
- reg-vm: closure-fuse invalidates defs on base-register clobber (wrong
  polymorphic dispatch)
- reg-vm (OSR eligibility): candidate gate admits GetField + combinator
  intrinsics; ListPush is OSR-admissible only for region-local lists; closure
  sink gated on statically-proven scalar captures
- reg-vm: native return-guard no longer lets a scratch FieldHandle escape
- reg-vm: try_native/try_osr refuse while mem_budget is armed (heap-writing
  native can allocate off-the-meter)
- spec: 7.1/7.2/10/3.1 reconciled with the heap-write transaction (journaled
  undo, commit-on-success, abort-on-bail)

Known gap (latent; precise resume default-off): a reassigned scalar param is
not restored on precise deopt -- blocked on J0.1 NativeTy-aware deopt state
maps (repro: precise_deopt_restores_reassigned_scalar_param, #[ignore]).

Verification (dev container): differential 33/0 (incl. force-deopt backends),
jit_acceptance 83/0, rsscript lib 275/0, vm-jit 81/0, deopt-stress 8/0,
default workspace build + lib 156/0, JIT perf gate PASS.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: olwang

.github/actions/rsscript-review/action.yml

@@ -132,7 +132,7 @@ runs:
         cp "$REVIEW_OUTPUT_FILE" "$COMMENT_FILE"
 
         # Write outputs
-        COMMENT_DELIMITER="RSSCRIPT_REVIEW_$(uuidgen 2>/dev/null || python3 -c 'import uuid; print(uuid.uuid4().hex)')"
+        COMMENT_DELIMITER="RSSCRIPT_REVIEW_$(uuidgen 2>/dev/null || date +%s%N)"
         {
           echo "comment<<$COMMENT_DELIMITER"
           cat "$REVIEW_OUTPUT_FILE"
@@ -168,7 +168,7 @@ runs:
         fi
 
         if [ -s "$CI_JSON_FILE" ]; then
-          REVIEW_STATUS=$(python3 -c 'import json,sys; print(json.load(open(sys.argv[1])).get("status","unknown"))' "$CI_JSON_FILE")
+          REVIEW_STATUS=$(perl -MJSON::PP -e 'local $/; my $d = decode_json(<>); print $d->{status} // "unknown";' < "$CI_JSON_FILE")
         elif [ $EXIT_CODE -ne 0 ]; then
           REVIEW_STATUS="fail"
         else

.github/workflows/jit-hardening.yml

@@ -0,0 +1,59 @@
+name: JIT hardening
+
+on:
+  workflow_dispatch:
+  schedule:
+    # Weekly bounded hardening sweep. Fuzz targets are capped by
+    # `-max_total_time=60`; this schedule gives them continuity without making
+    # every pull request pay the nightly/cargo-fuzz install cost.
+    - cron: "17 10 * * 6"
+
+concurrency:
+  group: jit-hardening-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  hardening:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+
+      - name: Build dev container
+        run: docker compose build dev
+
+      - name: Native JIT hardening gate
+        run: |
+          docker compose run --rm dev cargo test -p rsscript --lib register_window_tests --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript child_native --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --test runtime native_jit_fast_backends_include_deopt_every_safepoint --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --test runtime jit_acceptance_runs_ --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --test runtime native_jit_acceptance_reports_real_native_execution --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --test runtime native_jit_precompiles_cold_scalar_call_chains --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --test runtime native_jit_precompiles_handle_return_call_chains --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p vm-jit native_call_can_pass_flat -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --lib native_direct_dispatch_consumes_handle_return_compiled_call --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --lib native_direct_dispatch_passes_bool_args_and_return --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --lib native_direct_dispatch_passes_float_args_and_return --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --lib native_direct_dispatch_passes_flat_int_arg_to_compiled_call --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --lib native_direct_dispatch_passes_flat_float_arg_to_compiled_call --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --lib native_direct_dispatch_passes_flat_int_mut_arg_to_compiled_call --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --lib native_direct_dispatch_passes_handle_arg_to_compiled_call --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --lib native_direct_dispatch_invokes_mut_handle_compiled_call --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --lib precise_deopt_with_nested_child_native_frames_resumes_leaf_safepoint --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --test runtime report_profile_guided_pic_shows_hottest_first_order --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --test runtime report_shows_profile_guided_branch_feedback --features native-jit -- --test-threads=1
+          docker compose run --rm dev cargo test -p rsscript --test runtime report_groups_native_decline_reasons_by_count --features native-jit -- --test-threads=1
+          docker compose run --rm dev bash -lc 'RSS_DIFF_PROPTEST_CASES=16 RSS_DIFF_SHRINK_ITERS=0 cargo test -p rsscript --test differential backends_agree_on_seed_decoded_programs --features native-jit -- --test-threads=1'
+          docker compose run --rm dev cargo test --release -p rsscript --test runtime jit_perf_gate_against_baseline --features native-jit -- --test-threads=1 --nocapture
+          docker compose run --rm dev bash -lc 'rustup toolchain install nightly --component rust-src && target="$(rustc -vV | sed -n "s/^host: //p")" && RUSTFLAGS="-Zsanitizer=address" cargo +nightly test -Zbuild-std --target "$target" -p vm-jit native_scalar_call -- --test-threads=1 && RUSTFLAGS="-Zsanitizer=address" cargo +nightly test -Zbuild-std --target "$target" -p rsscript child_native --features native-jit -- --test-threads=1 && RUSTFLAGS="-Zsanitizer=address" cargo +nightly test -Zbuild-std --target "$target" -p rsscript forced_all_native_safepoints_exercises_child_native_deopt --features native-jit -- --test-threads=1 && RUSTFLAGS="-Zsanitizer=address" cargo +nightly test -Zbuild-std --target "$target" -p vm-jit guard_closure_id_passes_or_bails -- --test-threads=1 && RUSTFLAGS="-Zsanitizer=address" cargo +nightly test -Zbuild-std --target "$target" -p vm-jit direct_flat_reads_index_in_register -- --test-threads=1'
+
+      - name: Miri pure-core smoke
+        run: docker compose run --rm dev bash -lc 'rustup toolchain install nightly --component miri,rust-src && cargo +nightly miri test -p rss-testgen --lib'
+
+      - name: No-panic fuzz smoke
+        run: docker compose run --rm dev bash -lc 'rustup toolchain install nightly && (command -v cargo-fuzz >/dev/null || cargo install cargo-fuzz --locked) && cd fuzz && cargo +nightly fuzz run no_panic -- -runs=20000 -max_total_time=60'
+
+      - name: Native JIT differential fuzz smoke
+        run: docker compose run --rm dev bash -lc 'rustup toolchain install nightly && (command -v cargo-fuzz >/dev/null || cargo install cargo-fuzz --locked) && cd fuzz && cargo +nightly fuzz run differential --features native-jit -- -runs=5000 -max_total_time=60'

.github/workflows/jit-perf.yml

@@ -0,0 +1,38 @@
+name: JIT perf gate
+
+on:
+  workflow_dispatch:
+  pull_request:
+    branches: [main]
+    paths:
+      - ".github/workflows/jit-perf.yml"
+      - "benchmarks/vm-jit/**"
+      - "crates/rsscript/src/reg_vm/**"
+      - "crates/rsscript/tests/jit_acceptance.rs"
+      - "crates/vm-jit/**"
+  push:
+    branches: [main]
+    paths:
+      - ".github/workflows/jit-perf.yml"
+      - "benchmarks/vm-jit/**"
+      - "crates/rsscript/src/reg_vm/**"
+      - "crates/rsscript/tests/jit_acceptance.rs"
+      - "crates/vm-jit/**"
+
+concurrency:
+  group: jit-perf-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  perf-gate:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+
+      - name: Build dev container
+        run: docker compose build dev
+
+      - name: JIT perf gate
+        run: docker compose run --rm dev cargo test --release -p rsscript --test runtime jit_perf_gate_against_baseline --features native-jit -- --test-threads=1 --nocapture

AGENT.md

@@ -68,12 +68,14 @@ it as the lone exception, not the pattern. Spec: Constitution Article VIII, §2A
 rss check  [--core|--no-core] [--interface <f.rssi> ...] <file.rss>   # type/effect check
 rss check  <package-directory>            # check a package
 rss check  --explain <CODE>               # explain a diagnostic code, e.g. RS0026
-rss lint   <file.rss>                     # check + style lints
+rss check  --lint <file.rss>              # check + style lints
+rss fix    [--write] <file.rss>           # apply machine-applicable fixes
 rss fmt    <file.rss>                     # canonical formatter
-rss run    <file-or-package-dir> [-- <args>...]   # lower to Rust + build + run
+rss run    --vm <file-or-package-dir> [-- <args>...]  # fast VM run
+rss run    <file-or-package-dir> [-- <args>...]       # lower to Rust + build + run
 rss test   [--all] [--filter <substr>]
-rss dev    [--run] [--once] <file-or-dir> # watch loop
 rss pkg    [--json] [dir]            # package health check
+rss pkg    add <dep|dep@version|path>
 rss pkg    review [--json] [dir]     # review surface
 rss pkg    diff [--json] <old-dir> <new-dir>
 rss pkg    ci [--json] [dir]         # CI-facing package check
@@ -192,7 +194,7 @@ if count == 1 {
     Log.write(message: read "many")
 }
 
-for query in queries {            // `for` iterates a `List<T>` only (v0.6)
+for query in queries {            // `for` iterates a `List<T>` only
     DbConnection.query(conn: mut conn, sql: read query.sql)?
 }
 
@@ -325,7 +327,7 @@ Constructors are call-like and use the same named-arg + effect rules.
 
 ---
 
-## 7. Async (restricted in v0.6)
+## 7. Async (restricted v0.7 surface)
 
 ```rust
 features: async
@@ -336,9 +338,12 @@ async fn fetch(url: read Url) -> Result<Int, HttpError> {
 }
 ```
 
-Rules: `await` appears **only inside an `async fn`** and must directly consume an
-async call. There is no `Future`/`Poll`/`spawn` surface in v0.6 (single-isolate,
-cooperative). `spawn` and `Stream<T>` are review-visible but not executable yet.
+Rules: `await` appears **only inside an `async fn`**. The executable v0.7 surface
+supports direct `await`, structured `task_group { async let ... }`, `select`,
+bounded channels, streams, and `await for` in the single-isolate cooperative
+model. There is no public `Future`/`Poll`/`spawn` surface; unstructured `spawn`,
+async closures, public task handles, and cross-isolate task execution remain
+future work.
 
 ---