`cargo test` builds `ckc` under the `dev` profile and then RUNS it ~550 times.
opt-level 0 was therefore never a build-speed setting here — it multiplied by
every fixture in the tree. Measured on one core, full pipeline (front end +
lowering + Cranelift + link, `ckc disassemble`):

    opt-level 0 (before) ......................... 0.906 s
    deps at 2, workspace at 0 .................... 0.349 s
    deps at 2, workspace at 1 (now) .............. 0.122 s

7.4x, and it is close to free: an incremental rebuild after a real edit to
`ck_span` (15 crates) measures 1.079 s against 1.186 s before — inside the
noise. Dependencies go to 2 because Cranelift dominates codegen and is built
once and cached, so its level never reaches the edit loop.

The guards are untouched, which is the whole reason this is opt-level 1 and
not `inherits = "release"`. `opt-level` is orthogonal to `debug-assertions`
and `overflow-checks`; both stay on, verified in the built binary rather than
assumed — `ckc` still carries its `operator_table.rs` debug_assert sites and
its overflow panic path. `[profile.bootstrap]`'s reasoning applies with equal
force to the profile the tests run under.

`debug = "line-tables-only"` keeps file/line in every backtrace and drops the
records nothing here reads. The suite links ~57 binaries each statically
carrying the compiler and Cranelift, so this is the dominant term in link
time and disk: 65.5 MB -> 33.0 MB per test binary, the built set 5.3 -> 2.6 GB.

`capability` swept its 437 cells in a serial `for` loop — not because a cell
needed the one before it (each materializes its own project, links its own
binary into its own /work subdir, reads back its own meta stream) but because
that is how it was written. On 32 cores that is one core working and the rest
idle, which per cpu_broken.md is also the arrangement that concentrates wear.
It now runs across a bounded pool in `tests/common/mod.rs`, shared rather than
copied because `sizes_pin` needs the same thing next. Capped at the same 12 as
`.cargo/config.toml`'s `[build] jobs`: one number, one policy.

Order is preserved, and that is contractual, not cosmetic — the report prints
the exact block to write for each rejected cell, so a thread-shuffled report
could not be diffed between runs. Workers record each cell's index and the
results are sorted back before rendering. Verified by running the whole tree
at one worker and at twelve: the same eight cells, in the same order.

    capability, one build, workers 1 -> 12 ....... 32.18 s -> 3.37 s
    capability, HEAD -> here ..................... 76.95 s -> 3.37 s

`read_meta_stream` cost a flat five seconds whenever a run emitted nothing.
Its exit test was `!grew && !events.is_empty()`, unreachable while `events` is
empty, so an empty stream could only leave by the deadline. A bare `fn main`
boots no actor and a `ckc test` app with no `test fn` starts none; those runs
are finished, not slow. Split into a first-record grace and the original cap.

`ck_playground` is deleted. Its own manifest called it "throwaway scaffolding
to verify each slice's output visually while CkLang itself is not yet
runnable" — CkLang is runnable now, and it was last touched 2026-05-21. It
dragged eframe/egui/glow/wayland/x11 into the workspace: 307 of 372 lockfile
packages, 82.5%, existed only for it, and `cargo fmt`, `cargo clippy
--workspace --all-targets` and `cargo test --workspace` all paid for them. It
had no tests. Its R4 allow-list entry goes with it.

Full gate, warm on both sides: 5m20s -> 1m32s. The eight red capability cells
are unchanged and predate this: verified by running pristine HEAD.

@@ -73,0 +140,4 @@
+                    if let Some(result) = job(item) {
+                        collected
+                            .lock()
+                            .expect("the sweep results outlive every worker")

@@ -225,3 +199,3 @@
 /// with exactly one newline, so trailing-whitespace churn can never show up as
 /// a moved number.
-fn render(app: &str, sizes_exit: i32, tree: &str, run_exit: i32, report: &str) -> String {
+fn render(app: &str, sizes_exit: i32, tree: &str) -> String {