Conciseness

The body is dense with non-obvious specifics (TSan exitcode default 66, adaptive delay, cgo requirement, 5-15x overhead figures, the barrier-timeout-after-fix behavior) and does not re-explain basic concurrency concepts; minor trims remain, e.g. the Step 2 prose on asserting after join() duplicates the anti-patterns table and the References section double-lists references/go.md. Not score 5 only because of these small redundancies.

Actionability

Fully executable, copy-paste-ready examples cover the common cases: a complete Python Barrier test with error collection, a complete jcstress @State/@Actor/@Outcome test, a Java virtual-threads volume test, a Hypothesis property test, TSan build/run commands, and CI YAML. Not score 4: no key details are missing.

Workflow Clarity

Steps 1-7 are clearly sequenced (find state, force interleaving, detectors, jcstress, volume, checkpoint, CI) and Step 6 is an explicit validation checkpoint with an error-recovery feedback loop ("If step 1 passed ... widen the window ... and repeat step 1"), reinforced by the anti-patterns table. Not score 4: checkpoints are explicit, not implicit.

Progressive Disclosure

The body works as an overview with Go-specific detail appropriately split into references/go.md and references/goleak-filter-options.md, both of which exist, contain substantive content, are one level deep (no nested references), and are clearly signaled with descriptions of what they hold. Not score 4: no content that clearly belongs in a reference is inlined and navigation is easy.

Specificity

Quotes multiple concrete actions ("Forces interleavings with barriers and latches", "runs ThreadSanitizer, go test -race with goleak, or jcstress") plus named shared-state targets (cache, counter, pool, lazy singleton), comprehensively covering the skill's capabilities; not score 4, since coverage has no real gaps.

Completeness

Explicitly answers both: what ("Forces interleavings with barriers and latches, and runs ThreadSanitizer, go test -race with goleak, or jcstress") and when ("Use when a bug only appears under load on shared in-process state ... or a race needs a regression test before the fix") with concrete trigger phrases; score 4 would require a less specific 'when' clause.

Trigger Term Quality

Natural phrases like "bug only appears under load", "race needs a regression test", and tool names (ThreadSanitizer, jcstress) users would actually say, but common synonyms such as "flaky test", "intermittent", and "data race" are missing; not score 5, which requires comprehensive synonym coverage.

Distinctiveness Conflict Risk

A clear niche (in-process data races on shared mutable state) with distinct tool triggers, but closely related sister skills (deadlock detection, async ordering, MVCC isolation) occupy adjacent territory and the description does not delineate boundaries; minor overlap risk rather than minimal, so not score 5.