[ZongziForu]

Repeated polling currently probes every cross-generation thermal key, including keys absent from the connected Mac. On a MacBookPro17,1, 41 of the 50 temperature keys are absent, so each status() repeatedly pays for unsuccessful readKeyInfo calls.

This adds a connection-local firmware key inventory for the long-lived monitor and daemon. A key is skipped only after the entire inventory has been enumerated successfully. Partial/failed enumeration permits all reads and retries later; ordinary value-read failures never mark a sensor missing. App and daemon wake paths invalidate the inventory on their serialized hardware queues.

The existing performance work in #11 addresses polling cadence, successful key-info caching and observation. This PR targets absent-key probes separately and is based on current main. Default polling intervals, profiles, temperature thresholds and command behavior retain their existing implementation. One-shot CLI callers do not opt into inventory discovery.

Validation

• swift test: 157 tests passed, including five new inventory tests for different machines, failed/partial enumeration, malformed/duplicate entries and invalidation.
• swift build -c release: passed.
• Read-only hardware validation on MacBookPro17,1: the same nine temperature keys were returned with caching disabled/enabled.
• Three alternating runs using the included benchmark, 200 measured status() reads each after five warm-up reads:

Run	Inventory disabled, mean ms	Inventory enabled, mean ms
1	13.53	5.51
2	12.96	5.53
3	13.04	5.59

This is about a 58% reduction in warm status() wall time on this machine, not a whole-app CPU claim. The opt-in first read costs about 274–293ms to enumerate the inventory, once per connection or wake. Non-opted-in first reads remained around 12–14ms. Hardware/workload results may differ; other models are covered by inventory tests rather than physical validation.

Tools/benchmark-smc-status.swift includes build/run instructions; compare its default invocation with --inventory. It performs reads only and never controls fans.