Imported from microsoft/SynapseML (AGENTS.md). Install upstream with npx skills add microsoft/SynapseML. Copyright stays with the author.

SynapseML agent guide

Use this file for repository-wide rules. Human contributors should start with CONTRIBUTING.md.

Start here

1. Resolve the target branch (the PR base, not merely the checked-out feature branch), then use the branch context skill.
2. Read versions from build.sbt and environment.yml. Do not copy version numbers into this shared guide.
3. Use the narrowest relevant repository skill: Scala changes, local setup, and code review.
4. For requests to make one or more issues or PRs "5/5", "200% ready", or merge-ready, use the SynapseML PR loop.

Non-negotiable rules

• Never edit target/; generated files are overwritten.
• Never commit or print credentials, keys, connection strings, or .env files.
• Do not add RDD-based implementations. Use DataFrame/Dataset APIs so code works with Spark Connect and managed Spark modes.
• Do not rebase or force-push shared port branches.
• Do not add a hand-written __init__.py merely to re-export generated classes; a stale __all__ can hide public APIs.
• Keep existing public JVM signatures and serialized parameter shapes unless a breaking change is explicitly approved.

Ask before changing pipeline.yaml, workflows under .github/workflows/, release tooling, or dependency pins. These changes affect every branch and require CI evidence.

Branch model

Use the branch context skill for the active target list. Historical remote refs are not active merely because git branch -r lists them. Unqualified branch work covers only active targets.

Land cross-version changes on master; port branches receive them by merging master. When resolving a port-branch merge:

• keep the branch side only for version-driven differences;
• take the master side for ordinary fixes;
• combine both when each changed the same file for a different reason.

Reachability is not proof that a sync preserved content. Compare the merge base, master, and the port branch for every conflicted file, and verify that master additions remain present.

AGENTS.md and CONTRIBUTING.md must stay identical across branches, so neither may name a Spark, Scala, Java, or Python version, or a path containing one. Put branch-only facts in the branch context skill. Every other document — README.md, the website, and module docs — is free to be branch- and version-specific, because nothing requires those to match across branches.

Repository map

All modules depend on core; deep-learning also depends on opencv.

Each module follows src/main/scala, optional hand-written src/main/python, and src/test/{scala,python}. Follow nearby code before introducing a new pattern.

Scala-first API and code generation

Public SparkML behavior belongs in Scala. Classes mixing in Wrappable generate Python wrappers under target/scala-*/generated/src/python/synapse/ml/.

For a new or changed stage, verify:

• companion object extends DefaultParamsReadable[Stage];
• class accepts uid: String and has a random-UID no-arg constructor;
• Wrappable is present when a Python wrapper is required;
• SynapseMLLogging is mixed in, logClass(...) is called, and fit/transform is logged;
• copy(extra) preserves parameters, normally through defaultCopy(extra);
• transformSchema matches runtime output;
• save/load and generated wrapper behavior are tested.

Hand-written Python may extend a generated _ClassName wrapper when JVM delegation needs a Python convenience method. Do not move core behavior into Python.

Validation

Use the smallest command that proves the change, then expand when the affected surface requires it. Run SBT with the JDK selected by the local setup skill, not the machine default.

sbt <module>/compile
sbt <module>/Test/compile
sbt "<module>/testOnly fully.qualified.Suite"
sbt <module>/scalastyle <module>/Test/scalastyle
sbt codegen
black --check --extend-exclude 'docs/' .

Black is pinned in pyproject.toml; use that version.

Scala tests extend TestBase. Add positive, negative, schema, persistence, and end-to-end coverage where the behavior warrants it. A helper-only test is not proof that the public transformer path works.

Tests that require Azure credentials should skip when credentials are absent. Do not turn a skip into a pass by embedding a secret. Inspect service tests before running them because some create or delete cloud resources.

Pull requests and CI

• Use a conventional title: feat:, fix:, test:, docs:, ci:, or chore:.
• Target master unless the change exists only for a port branch.
• Resolve active and suppressed review findings; document why any finding is invalid.
• Trigger Azure validation with /azp run where supported. Branch-specific exceptions are documented in the branch context skill.
• Treat GitHub Actions as fast checks and pipeline.yaml as the full build.
• Do not equate green checks with correctness: compare before/after failures, inspect skipped tests, and verify the requested behavior directly.
• Rebase feature PRs onto the latest target before final validation. Merge master into shared port branches instead of rebasing them.

Keep this file useful

Add only durable, repository-wide guidance that changes an agent's decision. Prefer a link to the source of truth over copied commands, versions, or long examples. Put implementation detail beside the code, contributor process in CONTRIBUTING.md, and branch-specific facts in the branch context skill.