Cache behavior

The standalone renderer disables compiled caching by default. Supply an explicit Configuration::$cachePath or compiledCache to enable it. The CodeIgniter adapter defaults to WRITEPATH . 'cache/twig' for a FileHandler; other cache handlers use CICacheAdapter and a framework metadata store.

Compiled templates

Filesystem artifacts use a subclass of Twig's native cache. A persistent .twig-generation marker makes whole-cache clearing visible to existing and new renderers in a PHP worker. This marker is preserved when JSON metadata is reset. Keys are obtained from that cache and the environment; the integration does not reproduce Twig's hashing algorithm. invalidateTemplate(), batch invalidation and namespace invalidation use Twig's removable-cache API and forget the corresponding logical index entry. Loaded templates are refreshed in the current environment too.

warmup() and warmupAll() compile source and write it through the configured cache without rendering templates. Cache existence, freshness and source fingerprints decide whether compilation can be skipped. The force argument writes compiled source again, including when its PHP class was already loaded.

Metadata

Persistence\StateRepository manages these artifacts:

Logical key	Filesystem filename
compile.index	compile-index.json
compile.sources	compile-sources.json
disc.stats	discovery-stats.json
disc.list	discovery-stats-list.json
warmup.summary	warmup-summary.json
invalidations	invalidations.json

The compile index preserves the logical-name-to-boolean format. Source fingerprints are separate and do not contain template source. File writes use unique temporary files and atomic replacement, so readers do not see a partially written JSON document. Whole-document metadata updates are advisory and can replace concurrent updates; cache existence and source remain authoritative.

An optional CacheStoreInterface stores the same JSON payloads in a remote backend. The adapter's implementation reports medium ci in diagnostics. Optional metadata failures are logged and fall back to source discovery or recompilation. In-process discovery hits do not write metadata.

CodeIgniter remote compiled cache

Targeted invalidation deletes the actual compiled key. Whole-cache invalidation rotates a random generation instead of maintaining a shared read-modify-write array of every compiled key. Generation lookup is shared across all template keys in one render and refreshed at the next operation; persistent renderers observe external whole-cache clears. Old generations expire through retention: a positive cacheTtl is honored, while zero gives compiled payloads a retention of 86400 seconds. Metadata and generation keys can still have unlimited TTL.

Compiled PHP payloads retain HMAC verification. Configure a secret Config\Encryption::$key for authentication. The deterministic fallback is only corruption detection; it does not authenticate a cache controlled by an attacker. Never store trusted template source in an untrusted writable location.

The adapter preserves the established logical prefix convention: twig_, or _twig_ if the framework's global prefix already ends in an underscore. The framework handler is responsible for applying its global application prefix.

clearCache() removes compiled filesystem artifacts and known metadata, resets local state and invalidates discovery. It returns the number of filesystem artifacts removed, or zero for remote generation rotation. Set its reinitialize argument when the current renderer will continue to be used.

Warmup writes the shared class identity even after an environment reset; transient runtime class revisions do not become the authoritative warmup target. Targeted invalidation refreshes the selected backend generation and removes both the shared artifact and any distinct current-runtime artifact.

resetDiagnostics() resets optional metadata, with index/cache flags matching twig:reset-metrics. The Spark command delegates to this API, including remote backends; it does not scan an empty filesystem path or remove generation markers.