refactor(depot-client): split embedded depot transport

[NathanFlurry]

Description

Please include a summary of the changes and the related issue. Please also include relevant motivation and context.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[NathanFlurry]

• refactor(depot-client): split embedded depot transport #4970 : 2 dependent PRs (#4971 , #4972 ) 👈 (View in Graphite)
• fix(rivetkit): decode legacy v4 actor schedule args #4976
• fix(engine): install rustls provider with pools #4975
• fix(rivetkit): defer initialized persist until state exists #4974
• test(rivetkit): cover failed preflight disconnect handling #4973
• fix(rivetkit): hide pending connections during preflight #4969
• WIP: more fuzz tests #4962
• fix(rivetkit): wrap onMigrate in savepoints #4960 : 1 other dependent PR (#4963 )
• fix(pegboard): align drain grace defaults with stop threshold #4958 : 1 other dependent PR (#4966 )
• fix(rivetkit): preserve bridge error messages #4959
• fix(rivetkit): fire abort signal on shutdown finalize #4957
• fix(rivetkit): use startup kv preload #4956
• fix(client): flatten skipReadyWait option #4955
• ci(publish): add manual preview publish flow #4954
• fix(depot): add ltx decode diagnostics #4953
• fix(universaldb): preserve plain set values #4952
• fix(universaldb): align versionstamp operand encoding #4951
• fix(rivetkit): export database provider types #4950
• wip: kitchen sink agentic loop finish #4949
• chore(rivetkit): note duplicate admission logic #4948
• test(rivetkit): cover bypass fetch header forwarding #4947
• feat(kitchen-sink): add actor probe controls #4946
• fix(gateway): split actor response wait errors #4945
• fix(guard): handle bypass preflight before query parse #4944
• feat(kitchen-sink): add mock agent event log copy #4943
• fix(kitchen-sink): default mock agent to local endpoint #4942
• test(rivetkit): enable driver lifecycle regressions #4941
• test(rivetkit): verify cached websocket db refs exceed grace #4940
• fix(rivetkit-core): keep sleeping actors reachable during grace #4939
• test(rivetkit): cover async websocket close db access #4938
• fix(rivetkit): keep actors awake until keepAwake work finishes #4937
• fix(rivetkit): persist native onSleep state on errors #4936
• fix(rivetkit-core): allow dispatch during sleep grace #4935
• fix(rivetkit): make duplicate sleep requests idempotent #4934
• main

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[claude]

Code Review: refactor(depot-client): split embedded depot transport

Overview

This PR extracts EmbeddedDepotSqliteTransport (and its open_database_from_embedded_depot helper) out of depot-client into a new depot-client-embedded crate. The stated motivation -- keeping the engine-internal depot dependency out of the base depot-client crate that NAPI uses -- is sound and the split is clean.

The PR also removes rivet-pools from rivetkit-core, replacing pooled reqwest client calls with Client::builder().build().

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What works well

• Correct dependency boundary. depot-client no longer depends on the engine-internal depot crate. The new crate is small and focused.
• Module doc comment in depot-client-embedded/src/lib.rs is clear and explains why the split exists.
• Workspace member ordering groups the three depot-client* crates together alphabetically.
• Call-site update in pegboard-envoy/src/ws_to_tunnel_task.rs is minimal and correct.

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Issues / observations

1. Reqwest client lifecycle change (minor)

rivet_pools::reqwest::client() is a global singleton (OnceCell) that sets user_agent: RivetEngine/{version}, a 30-second global timeout, and shares a single connection pool across all callers.

The replacement Client::builder().build() creates a new client on every call with no shared state, no user agent, and no global timeout.

Correctness risk is low: both probe_existing_engine and wait_for_engine_health already set per-request timeouts (1 s each), and ensure_local_normal_runner_config is a one-shot startup call. But connection reuse between the three startup callers is lost. If this is intentional, a LazyLock<reqwest::Client> local to those files would restore connection reuse without re-adding the rivet-pools dependency.

2. Redundant [lib] section in depot-client-embedded/Cargo.toml (nit)

crate-type = ["lib"] is the Cargo default and can be dropped entirely.

3. No test coverage noted

The new crate is essentially a move-and-rename, so existing integration tests through pegboard-envoy should still cover it. The PR template test section is blank -- worth noting which tests exercise open_database_from_embedded_depot so the refactor is verifiably safe.

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Summary

The dependency split is the right architectural call and the implementation is clean. The main follow-up is whether the per-call reqwest client creation vs. the old shared-pool behavior is intentional. Otherwise this is a good change.