Add observation for serde_bare

[MasterPtato]

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[MasterPtato]

Stack for rivet-dev/rivet

• #5552 [slopfix] fix(universaldb): match fdb conflict semantics in …
• #5551 [slopfix] fix(universaldb,util,pegboard-envoy): index dedup …
• #5398 feat(kitchen-sink): add churnDb actor and seed driver for co …
• #5397 chore: Clean up
• #5382 [slopfix] docs(self-hosting): correct postgres config format …
• #5356 [slopfix] fix(pegboard): decrement kv_storage_used metric on …
• #5354 [slopfix] refactor(universaldb,ups): single/multi-node udb o …
• #5353 [slopfix] perf(universaldb): fold postgres drain_batch into …
• #5342 [SLOP(claude-opus-4-8-high)] perf(universaldb): batch leader …
• #5341 [slopfix] docs(self-hosting): promote postgres from experime …
• #5340 [slopfix] fix(self-host): repair dev compose generation, kit …
• #5337 [SLOP(claude-opus-4-8-high)] feat(universaldb): graceful pos …
• #5336 [slopfix] test(universaldb): postgres leader failover + abor …
• #5335 [SLOP(claude-opus-4-8-high)] feat(ups): table-backed postgre …
• #5329 [SLOP(claude-opus-4-8-high)] feat(universaldb): postgres lea …
• #5327 [SLOP(claude-opus-4-8)] feat(pegboard-envoy): rate-limit env …
• #5326 [SLOP(claude-opus-4-8)] feat(util): add rate limiter primiti …
• #5322 [SLOP(claude-opus-4-8)] feat(rivetkit-core): add serde durat …
• #5321 Add observation for serde_bare 👈
• #5320 Add observation and ser/de metrics for serde calls
• #5314 [SLOP(claude-opus-4-8-medium)] chore: add profiling cargo pr …
• #5306 [SLOP(claude-opus-4-8)] fix(kitchen-sink): serve built front …
• main

Get stack: forklift get 5321
Push local edits: forklift submit
Merge when ready: forklift merge 5321

_{change oskoutmw}

[claude]

Code Review

Summary

This PR adds observability (latency timing + serialize/deserialize size histograms) to raw serde_bare call sites by routing them through the rivet_util::serde::bare_from_slice! / bare_to_vec! macros, and does the same for one serde_json::from_str call in gasoline via json_from_str!. Mechanical, wide-reaching, but low risk in intent.

Issues Found

Build-breaking: rivet-depot-protocol is missing the rivet-util dependency

engine/sdks/rust/depot-protocol/src/versioned.rs now calls rivet_util::serde::bare_from_slice!(payload) and rivet_util::serde::bare_to_vec!(&data) (lines 24 and 31), but engine/sdks/rust/depot-protocol/Cargo.toml was not updated to add rivet-util.workspace = true. Every other crate touched by this PR (depot, engine, epoxy, gasoline, pegboard-runner, pegboard, runner-protocol, data, envoy-protocol, epoxy-protocol, ups-protocol) already has rivet-util as a dependency, and Cargo.lock confirms rivet-depot-protocol's dependency list still has no rivet-util entry:

```
[[package]]
name = "rivet-depot-protocol"
...
dependencies = [
"anyhow",
"rivet-vbare-compiler",
"serde",
"serde_bare",
"vbare",
]
```

Since rivet_util::... is invoked by its crate path directly in versioned.rs, this needs rivet-util declared in that crate's own Cargo.toml, not just transitively available -- cargo check -p rivet-depot-protocol should fail to resolve the rivet_util crate name. Fix: add rivet-util.workspace = true to engine/sdks/rust/depot-protocol/Cargo.toml (and regenerate the corresponding Cargo.lock entry).

Minor: doc-comment copy/paste error in engine/packages/util/src/serde.rs

Lines 81 and 96 both now read /// Wraps \rivet_util::serde::bare_to_vec!` with observability.Line 81 correctly documentsbare_to_vec!, but line 96 documents bare_from_slice!and should referencebare_from_slice!(or the underlyingserde_bare::from_slice), not bare_to_vec!`.

What Looks Good

• Every other OwnedVersionedData impl and FormalKey impl in the touched protocol/depot/pegboard crates is consistently migrated, including the version-specific match arms (each version keeps its own deserialize/serialize path, no accidental collapsing of variants).
• The rivet-util-serde to rivet-util dependency swap in envoy-protocol/Cargo.toml (and the pegboard-runner/Cargo.toml addition) is consistent with the macros living in rivet_util::serde.
• The compat_ack_tunnel_message change in pegboard-runner/src/ws_to_tunnel_task.rs correctly adds an explicit : protocol_v2::ToServer type annotation since the macro doesn't support a turbofish.
• The gasoline StateGuard::new change from rivet_util::observe!(serde_json::from_str::<T>(guard.0.get())?) to rivet_util::serde::json_from_str!(guard.0.get())? is semantically equivalent: type inference still resolves T from the surrounding Self { ... inner: value } struct literal, and json_from_str! already wraps with observe! plus adds a size histogram.
• The engine/packages/engine/src/commands/udb/cli.rs changelog-entry roundtrip check preserves its original early-continue fallback behavior on both the deserialize and reserialize failure paths.
• No unbounded metric labels introduced -- the location label on SERIALIZE_SIZE/DESERIALIZE_SIZE is a compile-time file:line:column, bounded by call-site count.
• No wire-format/schema changes; this is purely instrumentation at existing call sites.

Suggestion

Given cargo check -p rivet-depot-protocol (and anything depending on it, e.g. depot) should currently fail, it would be worth confirming CI actually ran a full workspace build/check on this PR before merge.