[agentydragon]

Central sampler currently puts transactional state, Runner effects, provider I/O and RPC admission in one root package. Move its durable state and transactions to internal/sessionstore, with tests beside the authority they exercise. Drop redundant store_ filename prefixes inside that owner.

Provider request preparation now takes a concrete recipe. Projection, freezing, stored bytes and intent insertion still run after the same owner/interrupt/pending checks inside the same transaction; network calls remain in the runtime. Pure tool schemas live in the existing internal/toolcontract. Retry policy remains runtime-owned, and native-frame classification remains executor-owned.

History’s real export/recovery/projection tests use a narrowly visible TESTONLY sampler source rather than importing a private Store or replacing it with a mock. Preserve the live native provider stream fixtures, export/checkpoint assertions, recovery-prefix checks and late-evidence fencing. Adoption tests move with Store. No migration, stored bytes, auth, protocol or lifecycle policy changes; Executor, resident runtime and RPC extraction follow separately.

Validation: Store/root libraries compile; all four affected test/binary build targets passed with keep-going; changed-file and commit hooks passed. Parent review verified all 141 production SQL literals unchanged and all 290 existing sampler test functions retained, checked test registration, the transaction preparation point and History fixture operation order. All four behavioral suites passed: Store, sampler unit (including native frame mapping), real History ingress, and sampler integration. The first integration run exposed a missing exec encoding in the request-read test fixture; setting it to JSON passed the focused rerun. Production behavior was unchanged. Hosted checks track the published head separately.

• Core build: https://www.buildbuddy.io/invocation/2644e39d-2fe9-4949-ba3e-fe4b1c31fdaa
• Affected test/binary compilation: https://www.buildbuddy.io/invocation/a364b8aa-c35c-40db-a497-9405a1314cd8
• Store, sampler unit and History ingress: https://www.buildbuddy.io/invocation/91ef357b-a6e3-4206-9816-021e283633ee
• Sampler integration after fixture correction: https://www.buildbuddy.io/invocation/bc5315cb-e73d-411e-b5ee-24f8086f6ccd

Proposed, ready successor to #16227 in native stack #16208. Review commit: 6e459ce0f5.