feat: [4/6] add payload purge protocol and client lifecycle

[wangbill (YunchuWang)]

Summary

What changed?

• Add the exact pinned DTS LargePayloadPurge protocol and four generated JS/TypeScript bindings, with reproducible codegen integration.
• Add PascalCase-compatible DTOs/constants and authenticated purge calls on the effective existing sidecar channel, without importing or registering any future worker runner.
• Implement setting-first enable/disable, unversioned deduplicated fixed runner identity/status verification and SetBatchSize signaling.
• Correct single-instance purge routing independently of payload configuration, matching .NET management clients. Cover ordinary and entity IDs with payloads both disabled and enabled.

Why is this change needed?

• Phase 4/6 of the requested large-payload implementation split. This PR's base is phase 3's branch, so its diff excludes previously reviewed phases.
• Behavioral reference: durabletask-dotnet 91739687. The complete stack preserves the original implementation at c9b53fcb3ab8585c4b3b22f9c0500cc9dd122c5a, with the documented instance-kind routing correction.

Issues / work items

• Resolves: N/A (user-requested phased feature review).
• Related: original oversized PR #387. It is preserved while the coordinator verifies this replacement stack.

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Project checklist

• Release notes are not required for the next release
  • Otherwise: Notes added to CHANGELOG.md
• Backport is not required
  • Otherwise: Backport tracked by issue/PR #issue_or_pr
• All required tests have been added/updated (unit tests, E2E tests)
• Breaking change?
  • If yes:
    • Impact: Explicit ordinary instance IDs now set isOrchestration=true even when the management client has no payload store. Entity IDs remain false; timeouts/completion results are preserved.
    • Migration guidance: No blob credential is needed to manage the setting or route a purge. A compatible .NET worker or phase 5 JavaScript worker is needed for the cleanup job. Do not release partial phases.

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AI-assisted code disclosure (required)

Was an AI tool used? (select one)

• No
• Yes, AI helped write parts of this PR (e.g., GitHub Copilot)
• Yes, an AI agent generated most of this PR

If AI was used:

• Tool(s): GitHub Copilot.
• AI-assisted areas/files: This phase's source, regression tests, and directly related metadata/documentation.
• What you changed after AI output: Split the implementation along independently buildable boundaries; retained focused regression evidence and removed unrelated formatting-only changes. Human review is still required.

AI verification (required if AI was used):

• I understand the code and can explain it
• I verified referenced APIs/types exist and are correct
• I reviewed edge cases/failure paths (timeouts, retries, cancellation, exceptions)
• I reviewed concurrency/async behavior
• I checked for unintended breaking or behavior changes

These human attestations are intentionally left unchecked.

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Testing

Automated tests

• Result: Passed locally for this phase, without later-phase files.
• npm ci --offline --no-audit --no-fund — passed after establishing the missing test runner.
• npm run build and npm run lint — passed without the later runner or worker registration.
• npm run test:unit -w @microsoft/durabletask-js -- --runTestsByPath test\payload-purge-client.spec.ts test\client-purge.spec.ts test\payload-transport.spec.ts test\client-wait-grpc.spec.ts — passed 53 tests in 4 suites.
• The new no-payload ordinary-ID regression failed on the original conditional flag, then passed after the unconditional instance-kind correction. All 27 purge tests pass, including four enabled/disabled kind cases and preserved timeout/completion behavior.
• Generated JS and pinned .NET protobuf descriptors compared byte-for-byte and matched SHA256 5DDA0563E9A4F61340C6A975AF8CB5994863766674F24C0B561AB037C3335569.
• bash.exe -n tools\generate-grpc-javascript.sh — passed.
• git diff --check yunchuwang-payload-phase-3-blob...HEAD — passed.
• Hosted CI: pending/not inferred. Existing main-base filters mean some workflows will not run for stacked PRs; no workflow triggers were broadened.

Manual validation (only if runtime/behavior changed)

• Environment (OS, Node.js version, components): Windows, Node.js v24.14.0; loopback gRPC servers with authenticated metadata assertions; pinned .NET descriptor comparison.
• Steps + observed results:
  1. Materialized this phase on its declared predecessor, with no future-phase imports.
  2. Ran the exact owning checks above and inspected the incremental patch.
  3. Kept the original feature branch/history and primary user checkout unchanged.
• Evidence (optional): Full local logs are session artifacts, not repository changes.

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Notes for reviewers

Merge order	Phase	PR	Base branch
1	Core contracts	#388	main
2	SDK integration	#389	yunchuwang-payload-phase-1-core
3	Azure Blob provider	#390	yunchuwang-payload-phase-2-sdk
4	Purge protocol/client	#391	yunchuwang-payload-phase-3-blob
5	Purge worker	#392	yunchuwang-payload-phase-4-client
6	Release/usage/consumers	#393	yunchuwang-payload-phase-5-worker

Merge 1 → 2 → 3 → 4 → 5 → 6. Each PR targets its predecessor; retarget the next PR only after its prerequisite merges. Do not publish packages or describe a partial phase as the complete feature.

• Generated-code noise is isolated here: the four generated binding files account for 1,684 added lines. Start review with the 56-line .proto, the DTOs and client lifecycle; bindings were generated, not manually edited.
• No worker runner is imported or registered. The management API can use an existing compatible .NET worker; the JavaScript runner follows in phase 5.
• The routing correction is supported by the .NET transport and proto field contract; no runtime data-loss claim is made.
• Full live DTS/mixed-.NET execution has not been run locally (Docker daemon unavailable). The final phase records aggregate local Blob/Azurite, source/wire interoperability and packed-consumer evidence without claiming absent hosted checks.