docs(litellm-rust): add provider coding standards

[devin-ai-integration]

Linear ticket

Pre-Submission checklist

• My PR's scope is as isolated as possible; it only solves 1 specific problem

Type

📖 Documentation

Changes

Adds litellm-rust/crates/CODING_STANDARDS/PROVIDER_CODING_STANDARDS.md, a numbered ruleset for adding or changing an LLM provider/route in litellm-rust, derived from the existing AGENTS.md / CLAUDE.md conventions and the OCR reference port.

The rules are grouped so a contributor can follow them top-to-bottom:

• Provider resolution: always resolve provider/model first via get_custom_llm_provider, resolve once in prepare.rs
• Transforms and base config: a route defines a base config trait with transform_request/transform_response; each provider implements it as a const <PROVIDER>_<ROUTE>_CONFIG, implementing only the transforms while inheriting shared trait defaults so future providers reuse existing logic
• Boundaries: core pure, ai-gateway I/O, python-bridge thin; no provider branches in generic files; thin entry point delegating to CallLifecycle::run_request; constants in constants.rs
• Types and errors: typed contracts only (no bare serde_json::Value), failures as typed CoreError values, no panics, no mutation, early returns, intentional Python-parity output shape
• Safety: never log bodies/secrets, treat blank config as absent, host I/O sets timeouts and reuses a shared client
• Tests and rollout: required transform test set plus *_match_python parity, lifecycle/hook tests, off-by-default behind Python parity tests
• Checks: the cargo fmt/clippy/test commands to keep green

Docs-only; no code paths change.

QA runbook

N/A (docs-only)

Final Attestation

• The tests check the right things, including the edge cases, and regressions in the respective real-world customer use-cases are not possible after this PR

Link to Devin session: https://app.devin.ai/sessions/db90b4ee508f4e81b5c19568c03cd157
Requested by: @ishaan-berri

[devin-ai-integration]

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[greptile-apps]

Greptile Summary

This is a docs-only PR adding litellm-rust/crates/CODING_STANDARDS/PROVIDER_CODING_STANDARDS.md, a 22-rule guide for how to add or change an LLM provider in the Rust port of litellm. No production code paths are modified.

• Defines provider resolution, transform/config, boundary, typing, safety, test, and pre-push check rules for the litellm-rust crate, using the OCR provider as a reference implementation.
• Adds the doc as a new file inside litellm-rust/crates/CODING_STANDARDS/ rather than in the dedicated litellm-docs repo, which conflicts with the repository's rule that documentation must live there.

Confidence Score: 3/5

No production code changes, but the single added file is placed in this repo contrary to the team's stated policy for documentation.

The coding standards document is well-structured and its content looks reasonable, but it is being added directly to this repo in violation of the rule that docs must go into the litellm-docs repo. The right location needs to be confirmed by a maintainer before merging.

litellm-rust/crates/CODING_STANDARDS/PROVIDER_CODING_STANDARDS.md — confirm with maintainers whether this belongs here or in litellm-docs.

Important Files Changed

Filename	Overview
litellm-rust/crates/CODING_STANDARDS/PROVIDER_CODING_STANDARDS.md	New markdown coding standards doc for litellm-rust provider development; violates the repo rule that documentation must live in the litellm-docs repo rather than this repository.

_{Reviews (1): Last reviewed commit: "docs(litellm-rust): add provider coding ..." | Re-trigger Greptile}

[greptile-apps]

Documentation should live in the litellm-docs repo

This repository has a rule that documentation additions must go into the litellm-docs repo, not this one. Adding PROVIDER_CODING_STANDARDS.md here adds prose docs directly to the main repo rather than the dedicated docs location. The file should be moved to the litellm-docs repo, or — if the intent is for it to serve as a machine-readable/tooling artifact for contributors working in this repo (similar to AGENTS.md / CLAUDE.md) — that distinction should be clarified in the PR description and confirmed by a maintainer.

Rule Used: Prevent documentation from being added - needs to ... (source)

Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[codspeed-hq]

Merging this PR will not alter performance

✅ 31 untouched benchmarks

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_{Comparing litellm_rust_provider_coding_standards (867575a) with litellm_internal_staging (010b200)¹}

Footnotes

1. No successful run was found on litellm_internal_staging (6f4f4f6) during the generation of this report, so 010b200 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩