## Problem
`runtime::config::tests::validates_unknown_top_level_keys_with_line_and_field_name`
intermittently fails during `cargo test --workspace` (witnessed during
#147 and #148 workspace runs) but passes deterministically in isolation.
Example failure from workspace run:
test result: FAILED. 464 passed; 1 failed
## Root cause
`runtime/src/config.rs::tests::temp_dir()` used nanosecond timestamp
alone for namespace isolation:
std::env::temp_dir().join(format!("runtime-config-{nanos}"))
Under parallel test execution on fast machines with coarse clock
resolution, two tests start within the same nanosecond bucket and
collide on the same path. One test's `fs::remove_dir_all(root)` then
races another's in-flight `fs::create_dir_all()`.
Other crates already solved this pattern:
- plugins::tests::temp_dir(label) — label-parameterized
- runtime::git_context::tests::temp_dir(label) — label-parameterized
runtime/src/config.rs was missed.
## Fix
Added process id + monotonically-incrementing atomic counter to the
namespace, making every callsite provably unique regardless of clock
resolution or scheduling:
static COUNTER: AtomicU64 = AtomicU64::new(0);
let pid = std::process::id();
let seq = COUNTER.fetch_add(1, Ordering::Relaxed);
std::env::temp_dir().join(format!("runtime-config-{pid}-{nanos}-{seq}"))
Chose counter+pid over the label-parameterized pattern to avoid
touching all 20 callsites in the same commit (mechanical noise with
no added safety — counter alone is sufficient).
## Verification
Before: one failure per workspace run (config test flake).
After: 5 consecutive `cargo test --workspace` runs — zero config
test failures. Only pre-existing `resume_latest` flake remains
(orthogonal, unrelated to this change).
for i in 1 2 3 4 5; do cargo test --workspace; done
# All 5 runs: config tests green. Only resume_latest flake appears.
cargo test -p runtime
# 465 passed; 0 failed
## ROADMAP.md
Added Pinpoint #149 documenting the gap, root cause, and fix.
Closes ROADMAP #149.
bc259ec6f9