Commissioning Proxy PR2: Add CP Cluster Server and Unit Tests  (#72625)

* CommissioningProxy: add cluster definition and generated code

* CommissioningProxy: add cluster server, delegate and unit tests

* Remove PythonProxyCommissioner, CHI, add CachedResults

* Adds missing CP auto-gen config

* Cluster Delegate Code Review

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* Updates after CP Gemini code review

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* CommissioningProxy: register cluster XML in ZAP codegen config

Add the generated registration for commissioning-proxy-cluster.xml that
was missing from the codegen config:

- zap_cluster_list.json: add COMMISSIONING_PROXY_CLUSTER (empty server
  dir; server entry deferred to the cluster-impl PR)
- tests.yaml: add the XML to the CI "Validate that xml are parsable" list
- commissioning-proxy-cluster.xml: regenerate header with
  attribute=in-progress; Git provenance now clean (no -dirty)

* Rebuild autogen files

* Removes CP active Python code

* [commissioning-proxy] Address PR2 review feedback

- Cluster owns ScanMaxTime/CacheTimeout storage + change reporting (delegate no longer forwards them).
- Command handlers return std::optional to own their async/sync response.
- Move endpoint id to the constructor; rename State_t -> State; default mock ctor/dtor in header.
- Remove dead CHIP_DEVICE_CONFIG_ENABLE_COMMISSIONING_PROXY test define.
- Rename backwards-compat suite -> codegen-integration and run it via src/BUILD.gn.
- Tests: drop 2 duplicate BgScan cases, add ScanMaxTime/CacheTimeout change-reporting tests.

* [commissioning-proxy] Replace delegate with transport-driver interface + subsystems

The cluster now owns all transport-agnostic bookkeeping via three internal
subsystems (SessionManager, ScanCache, ScanAggregator). Physical transport
work is handled by CommissioningProxyTransport driver objects registered via
RegisterTransport(); GetSupportedTransports() ORs all registered drivers.

CommissioningProxyDelegate.h is removed; NotifyAttributeChanged for writable
attributes (ScanMaxTime, CacheTimeout) is now always the cluster's responsibility.

Tests updated to use CommissioningProxyMockTransport (93 cases).

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* [commissioning-proxy] Fix GN include-checker failure in CommissioningProxyScanCache

CommissioningProxyScanCache.cpp included CommissioningProxyCluster.h, which
is intentionally excluded from the commissioning-proxy-server source_set
(compiled in the consumer's context via app_config_dependent_sources.gni).
GN's include-checker rejected it, failing ESP32, Linux, and ARM cross-compile.

Introduce ScanCacheObserver (three pure-virtual callbacks) in
CommissioningProxyScanCache.h. CommissioningProxyCluster inherits it;
the scan cache stores ScanCacheObserver& instead of CommissioningProxyCluster&.

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* [commissioning-proxy] Fix ASAN stack-use-after-scope in TestProxyMessageRequest_DuplicateRequest_Busy

CommissioningProxyCluster did not override Shutdown(). The explicit
cluster.Shutdown() call in tests only cleared mContext; subsystem teardown
only happened in the destructor. C++ destroys tester (which owns
MockCommandHandler) before cluster, so the destructor's mSessions.Shutdown()
→ delete pm → Handle::Release() reached a dead CommandHandler.

Override Shutdown() to clean up subsystems and transports. The destructor
delegates to it as an idempotent safety net (mTransportCount=0 guards the loop).

* [commissioning-proxy] Fix clang-tidy warnings in TestCommissioningProxyCluster

bugprone-argument-comment: argument comment must match the parameter
name exactly — /*maxSessions=*/ → /*aMaxSessions=*/.

bugprone-unchecked-optional-access: clang-tidy's dataflow analysis does
not see through the ASSERT_TRUE macro, so response-> after
ASSERT_TRUE(response.has_value()) is flagged. Replace with
response.value().field which throws bad_optional_access instead of UB
and is not flagged by the checker.

* [commissioning-proxy] Fix bugprone-unchecked-optional-access in tests

clang-tidy's dataflow analysis does not see through ASSERT_TRUE macros,
so response.value() after ASSERT_TRUE(response.has_value()) is still
flagged. Wrap each access in an explicit if (response.has_value()) block,
which creates visible control flow the checker can follow.

* [commissioning-proxy] Add braces to all bare if/for/while bodies

GCC 14.2 on Tizen raises -Werror=dangling-else when a brace-free
if body is a GTest EXPECT_* macro that expands to if/else internally.
Add explicit braces to all single-statement if/else-if/for/while
bodies across commissioning-proxy-server/ (46 sites in 7 files).

Also fix README: remove unverified spec section number, update
argument-comment names to match Config constructor parameters.

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* [commissioning-proxy] Add shared background-scan fabric registry

Extract the transport-agnostic ProxyBackGroundScan bookkeeping (per-fabric
transport/band records, lifetime timers, Start/Stop overlap arithmetic,
paused/deferred state) into CommissioningProxyBgScanRegistry so the BLE and
PAF transports stop duplicating it; transports supply only hardware
start/stop/clear hooks via HardwareControl. Adds 15 unit tests.

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* [commissioning-proxy] Document background-scan registry, fix build layout

Add CommissioningProxyBgScanRegistry to the README's subsystem and
architecture tables, fix the BgScanStart/BgScanStop signatures in the
driver example, and document its API and HardwareControl contract.

The cluster reads no transport build flags, so move
CommissioningProxyCluster.{h,cpp} into the cluster source_set and out of
app_config_dependent_sources.{gni,cmake}, matching chime-server, and
drop the stale comment naming the deleted CommissioningProxyDelegate.h.

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* Use WritAttribute and remove redundant comment

- WriteAttribute: use DefaultServerCluster::SetAttributeValue for
  ScanMaxTime and CacheTimeout instead of hand-rolling the
  compare/assign/NotifyAttributeChanged pattern. No behaviour change.
- tests/BUILD.gn: drop the historical backwards-compatibility note from
  the tests-codegen-integration comment

* CodeRabbitAI first checnges fix

Add the smaller fixes identified.

* Inject a TimerDelegate so cluster timer paths are testable

The session manager and scan aggregator called SystemLayer directly, so
tests could not drive expiry or exercise a StartTimer failure.

Both now take a chip::TimerDelegate; the aggregator and each pending
message are TimerContexts, and CodegenIntegration supplies the shared
DefaultTimerDelegate, so the cluster ctor gains a third parameter.
Adds CommissioningProxyMockTimer (multi-context with failure injection)
and 3 tests for the rollback paths, each confirmed to fail without them.

* Add new tests to use TimerDelegate

Adds 7 timer unit tests tests for bgscan lifetime expiry and
timer-arm failure, independent per-fabric lifetimes, cache TTL expiry,
rediscovery resetting the TTL, sweep re-arming, and the watchdog ending
a stalled aggregation. Each confirmed to fail against broken code.

* Make a rejected background-scan start leave nothing behind

BgScanRegistry::Start mutated the fabric table before the hardware start
and lifetime timer could fail, so a failed refresh destroyed a working
registration and cancelled its timer. Both fallible steps now run first
and the record is only replaced on success.

ProxyBackGroundScanStartRequest returned the first error while leaving
already-started transports scanning; those are now stopped on failure.

* Make background-scan records per fabric

Spec says "keep per fabric records", recording the sender's NodeID only to
authorise the matching Stop. Keying on the pair grew the table with fabrics
x nodes. The NodeID now sits in the record, Stop rejects a non-owner, and a
start from another node on the same fabric takes ownership.

* Tidy unsued #include and small tweaks

* Trim comments.

* Scan the union of each fabric's background-scan requests

Each node keeps its own request (a Stop is identified by NodeID and FabricID);
the fabric scans their union under one timer at the latest deadline, recomputed
on Stop, capped at 4 requests. Clearing is band-scoped: ClearCachedResults(bands).

* Give the CommissioningProxy cluster bounded, fabric-aware state

Added removed fabric's sessions, connect and background scans. MaxSessions and
MaxCachedResults now come from CHIPConfig.h, sizing the heap-free storage that
replaces std::map and raw new.

* Clear fabric request slot on re-arm failure

Add new tests and update REAME.md

* Fix CommissioningProxy lifecycle and validation gaps from review

Release a background-scan fabric whose lifetime timer cannot be re-armed
so a failed refresh cannot leave its requests scanning unbounded. Reject
reserved Transport bits in ProxyConnectRequest with InvalidCommand, as
the scan commands already does. Cancel the scan cache's sweep timer
from its destructor. Leave the mock transport's unanswered message
pending so the response timer is what resolves it.

* Consolidate CommissioningProxy unit tests

Merge or drop tests that re-asserted a covered path, table the read-only and
min-1 attribute checks, and give the registry tests a fixture. Add a
cross-command reserved-Transport-bit test; note why MaxSessions stays above 1.

* CP: Make MAX_SESSIONS default=1

* Add compile-time bounds on the three CP config macros

* Address PR review feedback on the Commissioning Proxy cluster server

Drop the unused CodegenIntegration Instance wrapper, its test target and the
mock_ember carve-out it needed. Type the transport interface's seconds params
as System::Clock::Seconds16, rename the session lookups, tidy the registry.

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>