Kobe API: Add jitosol_validators/:vote_account stake history endpoint

[ggnine-jito]

What

Adds GET /api/v1/jitosol_validators/:vote_account — one validator's JitoSOL stake-pool delegation per epoch, in a single call.

GET /api/v1/jitosol_validators/6hkfqeNAbURk7CmAQsP4Qm6WwHVF4LxHupEvQf7Tkrf1?start_epoch=900&end_epoch=1016
{
  "vote_account": "6hkfq…Tkrf1",
  "history": [
    { "epoch": 900, "jito_sol_active_lamports": 52700000000000 },
    …
  ]
}

• start_epoch / end_epoch are optional and inclusive; omit both for the full history.
• jito_sol_active_lamports is the same target_pool_active_lamports that jitosol_validators already serves; it is null for epochs where the validator was not in the pool's validator list (target_pool_staked == false), so "not in pool" and "0 stake" stay distinguishable.
• Ascending by epoch. Invalid pubkey or start_epoch > end_epoch → 400. Cached 60s per (vote_account, range) like the neighbouring wrappers.

Why

jitosol_validators returns every pool validator for a single epoch (~300KB), so charting one validator's history from jito.network means one request per epoch (see jito-labs/stake-pool-fe#917, which built a KV cache + backfill around that). This endpoint replaces that with one indexed read.

Changes

• core/src/db_models/validators.rs — ValidatorStore::find_by_vote_account(vote_account, start_epoch, end_epoch).
• api/src/schemas/validator.rs — request/response types.
• api/src/resolvers/query_resolver.rs — get_jitosol_validator_stake_history + #[cached] wrapper.
• api/src/main.rs — handler + route, next to validators/:vote_account.

Ops note

The query filters on vote_account (and optionally epoch). The repo doesn't create indexes in code, so please make sure the validators collection has an index covering { vote_account: 1, epoch: 1 } before/at deploy — without it this is a collection scan per cold request (~1.5k validators × ~420 epochs).

Verification

• cargo fmt --all --check, cargo clippy -p kobe-api -p kobe-core --all-features -- -D warnings, cargo check -p kobe-api — clean.
• Not exercised against a live Mongo from this machine; the query shape mirrors find() / get_highest_epoch() in the same store.

Refs MEV-12617.

[ggnine-jito]

CI note — the two red lint jobs are pre-existing, not from this PR:

• lint / lint: clippy result_large_err at core/src/rpc_utils.rs:27/39/56, which this PR doesn't touch. CI runs floating stable; the same job fails on ak/metrics (Aug 21). cargo clippy -p kobe-api -p kobe-core --all-features -- -D warnings is clean locally on 1.90.
• lint / security_audit: 6 RUSTSEC advisories in transitive deps; Cargo.lock is unchanged here. ak/metrics passed this job three days ago, so these are newly published advisories.

build, run_tests, and udeps pass.

[Copilot]

Pull request overview

Adds an API endpoint for retrieving one validator’s historical JitoSOL delegation by epoch.

Changes:

• Adds optional epoch-range filtering and ordered MongoDB retrieval.
• Adds request/response schemas, caching, resolver logic, handler, and route.
• Updates dependencies, audit exclusions, and boxes several large RPC errors.

Reviewed changes

Copilot reviewed 8 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
api/src/main.rs	Registers the stake-history endpoint.
api/src/schemas/validator.rs	Defines request and response models.
api/src/resolvers/query_resolver.rs	Implements cached history resolution.
api/src/resolvers/error.rs	Boxes Jito transaction errors.
core/src/db_models/validators.rs	Adds the historical validator query.
core/src/rpc_utils.rs	Boxes RPC errors.
cranker/src/utils.rs	Boxes client errors.
Cargo.lock	Updates transitive dependencies.
.cargo/audit.toml	Adds ignored security advisories.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.