Tag outgoing SDK calls with a lighter-agent-kit User-Agent

[kutay25]

Summary

Brand every HTTP request the kit issues through lighter-python with a User-Agent header so the server can attribute traffic to the agent kit (vs. web/mobile/arbitrary SDK callers).

Header format (RFC 7231 product-tokens):

User-Agent: lighter-agent-kit/0.1.0 lighter-python/1.0.8

Filter agent-kit traffic server-side with ^lighter-agent-kit/; the trailing token also lets you slice by SDK version.

Implementation:

• New helper tag_api_client(api_client) in scripts/_sdk.py that sets api_client.user_agent (the existing public setter on lighter.ApiClient).
• Applied at every lighter.ApiClient(...) and lighter.SignerClient(...) construction site (5 total: query.py ×2, paper.py ×2, trade.py ×1). For SignerClient the helper is applied to signer.api_client since the SDK constructs the inner ApiClient itself.
• SDK version resolved via importlib.metadata.version("lighter-sdk") so it tracks the actually-installed package; falls back to lighter.__version__ then "unknown".
• No changes to lighter-python. Uses the existing OpenAPI-generated user_agent property setter, which is the only existing source-tag mechanism in the SDK today.
• Two test files needed a new entry on the in-memory _sdk stub (sdk_mod.tag_api_client = lambda c: c) since they reconstruct _sdk with types.ModuleType.

End-to-end verification. Spun up a local HTTP capture server, pointed LIGHTER_HOST at it, and exercised every public-read entrypoint. All outgoing requests carried the new UA:

$ LIGHTER_HOST=http://127.0.0.1:29292 python3 scripts/query.py system status
[capture] GET /                  UA='lighter-agent-kit/0.1.0 lighter-python/1.0.8'

$ LIGHTER_HOST=http://127.0.0.1:29292 python3 scripts/query.py market list
[capture] GET /api/v1/orderBooks UA='lighter-agent-kit/0.1.0 lighter-python/1.0.8'

$ LIGHTER_HOST=http://127.0.0.1:29292 python3 scripts/query.py market stats
[capture] GET /api/v1/exchangeStats UA='lighter-agent-kit/0.1.0 lighter-python/1.0.8'

$ LIGHTER_HOST=http://127.0.0.1:29292 python3 scripts/paper.py refresh BTC
[capture] GET /api/v1/orderBooks UA='lighter-agent-kit/0.1.0 lighter-python/1.0.8'
[capture] GET /api/v1/orderBooks UA='lighter-agent-kit/0.1.0 lighter-python/1.0.8'

Default boilerplate UA before this change was OpenAPI-Generator/1.0.0/python (set by the auto-generated lighter/api_client.py:91).

pytest tests/ → 73 passed.

Review & Testing Checklist for Human

• Confirm the chosen UA format (lighter-agent-kit/<version> lighter-python/<sdk>) is what you want logged/aggregated server-side; locking it in here means existing dashboards/regexes will need to match ^lighter-agent-kit/.
• Sanity-check AGENT_KIT_VERSION = "0.1.0" placement in scripts/_sdk.py — this is now the single source of truth for the kit's version (replaces the literal in scripts/health.py, though this PR leaves health.py alone to keep the diff minimal). If you want to consolidate, follow up with a tiny PR.
• Run python3 scripts/query.py market list (or any read) against staging or mainnet and confirm a real request appears in your traffic logs with the expected UA.
• Decide whether trade.py writes (signed orders) should also be sampled to confirm the UA propagates on POST /sendTx* paths — this PR applies the same tag to SignerClient.api_client, so they should, but a single signed test order against testnet would close the loop end-to-end.

Notes

• WebSocket calls (lighter/ws_client.py) don't carry any tag and aren't used by agent-kit; out of scope.
• The helper is idempotent and returns the client, so it's safe to layer on top later (e.g. per-script granularity like lighter-agent-kit-trade/...) if you ever want that.
• Picked the User-Agent header rather than introducing a new X-Source header because UA is the only existing tagging convention in the SDK and presumably what web/mobile already use.

Link to Devin session: https://app.devin.ai/sessions/6048677bfdf448c88ba064cc4e9ea0bf
Requested by: @kutay25

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