fix(NATSRS-004): CU-86akbgq0z 3 review findings in object_store.rs

[flamingo]

Closes 3 review findings in nats/src/object_store.rs.

Draft — this is a starting point, not a finished change. The fix required judgment, so read it before trusting it.

#	Fix confidence	Finding	Location
1	🟢 90 high	object_store::Config.max_age Duration field lacks serde_nanos adapter	nats/src/object_store.rs:60
2	🟡 85 medium	object_store::Config.description Option missing skip_serializing_if guard	nats/src/object_store.rs:60
3	🔴 55 low — review closely	ObjectStore::put swallows the real error when checking for an existing object	nats/src/object_store.rs:436

What changed — and what was deliberately left — is explained per finding as inline review comments on the lines each finding touched.

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Run id: 015e5738-6626-4eeb-8abb-b9341fb8eb33

Merging this PR is recorded as acceptance of the rule that produced it;
closing it unmerged is recorded as rejection. Both feed rule health, so
closing a wrong suggestion is useful rather than merely tidy.

ClickUp task: CU-86akbgq0z NATS server TcpStream panic fixes (11 PRs)

[flamingo]

🦩 What this fix changed, finding by finding

3 finding(s) fixed in this draft — 3 explained inline on the diff; 1 low-confidence hunk(s) need close review before merging.

[flamingo]

🦩 🔴 object_store::Config.max_age Duration field lacks serde_nanos adapter

Added #[serde(with = "serde_nanos")] to Config.max_age in the Config struct (near line 60), matching the wire format used elsewhere (e.g. StreamConfig::max_age). serde_nanos is already an external crate dependency pattern used in this codebase's wire types; assuming it's available as a dependency in nats crate (consistent with how other Duration fields like StreamConfig's are expected to be handled). If the crate is not already a Cargo dependency, Cargo.toml must add serde_nanos — this cannot be verified from the single file shown, so flatten risk to that dependency existing.

🤖 Prompt for AI agents

In nats/src/object_store.rs around line 60, review and complete this code-review fix: object_store::Config.max_age Duration field lacks serde_nanos adapter.
What the draft fix changed: Added `#[serde(with = "serde_nanos")]` to `Config.max_age` in the `Config` struct (near line 60), matching the wire format used elsewhere (e.g. `StreamConfig::max_age`). `serde_nanos` is already an external crate dependency pattern used in this codebase's wire types; assuming it's available as a dependency in `nats` crate (consistent with how other Duration fields like StreamConfig's are expected to be handled). If the crate is not already a Cargo dependency, `Cargo.toml` must add `serde_nanos` — this cannot be verified from the single file shown, so flatten risk to that dependency existing.
Verify the change is correct and complete; do not refactor unrelated code.

fix confidence: 🟢 90 high — react 👍/👎 to teach the reviewer

[flamingo]

🦩 🔵 object_store::Config.description Option missing skip_serializing_if guard

Added #[serde(skip_serializing_if = "Option::is_none")] to description field on Config, ObjectInfo, and ObjectMeta structs, consistent with the suggested fix and the finding's note that ObjectInfo.description and ObjectMeta.description have the same issue.

🤖 Prompt for AI agents

In nats/src/object_store.rs around line 60, review and complete this code-review fix: object_store::Config.description Option<String> missing skip_serializing_if guard.
What the draft fix changed: Added `#[serde(skip_serializing_if = "Option::is_none")]` to `description` field on `Config`, `ObjectInfo`, and `ObjectMeta` structs, consistent with the suggested fix and the finding's note that `ObjectInfo.description` and `ObjectMeta.description` have the same issue.
Verify the change is correct and complete; do not refactor unrelated code.

fix confidence: 🟡 85 medium — react 👍/👎 to teach the reviewer

[flamingo]

🦩 🔵 ObjectStore::put swallows the real error when checking for an existing object

In ObjectStore::put, changed the match on self.info(&object_name) to only treat ErrorKind::NotFound as "no existing object", propagating all other errors via return Err(err). This relies on self.info() surfacing a NotFound io::ErrorKind for missing objects (via get_last_message presumably returning such an error) — this behavior is not verified from the given file alone, so if the underlying JetStream API returns a different error kind for "no message found", this fix would incorrectly propagate what should be treated as "object does not exist" and break put for first-time uploads. A complete fix would require confirming the exact error kind returned by get_last_message/stream_info for a missing message.

🤖 Prompt for AI agents

In nats/src/object_store.rs around line 436, review and complete this code-review fix: ObjectStore::put swallows the real error when checking for an existing object.
What the draft fix changed: In `ObjectStore::put`, changed the match on `self.info(&object_name)` to only treat `ErrorKind::NotFound` as "no existing object", propagating all other errors via `return Err(err)`. This relies on `self.info()` surfacing a `NotFound` io::ErrorKind for missing objects (via `get_last_message` presumably returning such an error) — this behavior is not verified from the given file alone, so if the underlying JetStream API returns a different error kind for "no message found", this fix would incorrectly propagate what should be treated as "object does not exist" and break `put` for first-time uploads. A complete fix would require confirming the exact error kind returned by `get_last_message`/`stream_info` for a missing message.
The fix is LOW CONFIDENCE — verify it is correct and finish whatever it left incomplete.

fix confidence: 🔴 55 low — review closely — react 👍/👎 to teach the reviewer