feat(sidecar): gov-vote handler (PR-B of #163)

[bdchatham]

First user-facing gov sign-tx handler. Composes on the sign-tx foundation (#170) and hardening (#173).

Summary

• New `TaskGovVote` task type + `sidecar/tasks/gov_vote.go` handler that builds Cosmos gov v1beta1 `MsgVote` and delegates to `SignAndBroadcast`.
• `GovVoteTask` Go client SDK helper.
• No chain-query idempotency — chain handles last-write-wins on `(proposalID, voter)`; caller's request is authoritative.
• Also closes sign-tx hardening: typed RPCError discriminator, ctx-plumbing audit, fee_payer/granter assertion #172 item 3 (deferred from sidecar: harden /tx?hash= discriminator and lock ctx-plumbing audit #173): `TestSignedTxHasNoFeePayerOrGranter` decodes the signed proto Tx and asserts `AuthInfo.Fee.Payer` / `Granter` are empty strings.
• Exported `ParseVoteOption` so client and server share one canonical option set (no drift).
• Two follow-ups tracked in Per-handler idempotency review + TaskResult.Output engine extension #174: per-handler idempotency review template (load-bearing once a non-idempotent sign-tx handler ships), `TaskResult.Output` engine extension.

Test plan

• `TestParseVoteOption` table — case-insensitivity, kebab alias, empty/unknown rejection
• `TestBuildVoteMsg` subtests — happy path (incl. `ValidateBasic` assertion), zero proposalID, invalid option, nil keyring, empty keyName, missing key — all Terminal
• `TestSignedTxHasNoFeePayerOrGranter` — proto-level fee-payer/granter empty assertion
• `go build ./...` clean
• `go test ./... -count=1` clean (all packages)
• `go test -race ./sidecar/tasks/` clean
• `golangci-lint run --new-from-rev=origin/main ./...` reports 0 issues
• Coral trio cross-review (platform / kubernetes / security) — synthesized findings applied; remaining deferred to Per-handler idempotency review + TaskResult.Output engine extension #174

🤖 Generated with Claude Code

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Note

High Risk
Adds a new sign-and-broadcast task that can submit on-chain governance votes using the validator’s keyring, which is security-sensitive (especially given the sidecar API exposure). Also introduces new invariants around tx fee payer/granter enforced by tests, but mistakes could still result in unintended transactions/fees.

Overview
Adds a new gov-vote task end-to-end: registers engine.TaskGovVote in serve.go, defines the task type in engine/types.go, and implements sidecar/tasks/gov_vote.go to build a gov v1beta1 MsgVote and delegate signing/broadcasting to SignAndBroadcast.

Extends the Go client SDK (sidecar/client/tasks.go) with a typed GovVoteTask (validation + wire params) and shares vote-option parsing via exported tasks.ParseVoteOption.

Hardens tx signing tests by capturing broadcast tx bytes and asserting, at the protobuf level, that AuthInfo.Fee.Payer and AuthInfo.Fee.Granter are empty, preventing accidental fee delegation regressions.

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Cursor Bugbot has reviewed your changes and found 1 potential issue.

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Missing SubmitGovVoteTask client convenience method

Low Severity

Every other task type in the client SDK (SnapshotRestoreTask, AwaitConditionTask, ConfigApplyTask, etc.) has a corresponding Submit*Task convenience method on SidecarClient in client.go that calls Validate() before delegating to SubmitTask. The new GovVoteTask defines Validate(), TaskType(), and ToTaskRequest() but has no matching SubmitGovVoteTask method, breaking the established SDK pattern. Callers using the generic SubmitTask path can accidentally skip client-side validation.

 

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