fix(static-cache): count each outcome once per request, for real

[sylvesterdamgaard]

The guard in StaticCacheTelemetry::recordOutcome() promised "count each outcome once per request", but RECORDED_KEY was a single last-value slot:

if ($request->attributes->get(self::RECORDED_KEY) === $result) {
    return;
}

That suppresses an immediate repeat and nothing else. The very sequence the comment was written for goes miss → write → miss, and the write in the middle clears the way for the second miss to be counted.

It is real, not theoretical

The application cacher only reports a page once its prepared response has been snapshotted, so a probe after cachePage() genuinely misses again. Driving the sequence through the real cacher on main:

operation=miss  value=2.0
operation=write value=1.0

One page serve, two misses. statamic.static_cache.operations is what a hit-ratio panel divides by, so this doesn't just add noise — it biases the ratio toward misses, and only for pages that were actually rendered and cached.

The fix

The promise was right; the implementation was wrong. The request attribute now holds the set of outcomes already counted rather than the last one.

A second effect worth naming: the repeat probe used to overwrite the span's statamic.static_cache attribute back to miss after the write. It now stays write, which is what recordWrite()'s own docblock says should happen ("the span attribute is overwritten so the final value tells the fuller story"). The existing span assertion already expected write — it passed only because nothing exercised the repeat.

Test

tests/Feature/StaticCacheTest.php drives probe → cache → probe through the resolved cacher and asserts the vocabulary plus the per-series totals, using 2.4's metric inspection:

$operations->assertLabelValues('operation', ['miss', 'write']);

expect($operations->withLabels(['operation' => 'miss'])->total())->toBe(1.0)
    ->and($operations->withLabels(['operation' => 'write'])->total())->toBe(1.0);

Before the fix it fails with Failed asserting that 2.0 is identical to 1.0. Note that assertLabelValues passes either way — the vocabulary was never wrong, only the counts — which is why this needed the totals and not just an exact label set.

pint, PHPStan and 78 tests green.

Note for whoever merges

Touches tests/Feature/StaticCacheTest.php, as does #2 (additively, at the end of the file). Whichever lands second wants a trivial rebase.