Analysis API Mark Internal Apis

Mark Internal APIs in Analysis API Implementation Modules

Public declarations in Analysis API implementation modules should not be exposed to users. They should be internal or annotated with a visibility annotation. The codebase test AbstractAnalysisApiInternalApiTest already finds unmarked declarations and chooses a default annotation per module/package. This skill runs that test in auto-apply mode, then refines each freshly marked declaration: downgrade to internal when it has no callers outside its module, upgrade @LLFirInternals to @KaImplementationDetail when its callers reach outside analysis/low-level-api-fir/, and keep the rest. Finally, fix any "internal exposed through public API" build errors by re-promoting internal declarations to @KaImplementationDetail.

Reference: Read Guard API Endpoints with Annotations for the full annotation guide and placement rules.

Inputs

Module selection (required)

Use AskUserQuestion to present a selection of modules. The user must pick one. Only modules that have a per-module codebase test are listed here:

Throughout this skill, <module> and <gradle-task> refer to the user's selection.

Optional flags

Annotations Reference

The codebase test owns the initial choice of marker for each unmarked declaration. The test's per-module logic lives in the suggestedAnnotation overrides:

• analysis-api-fir, analysis-api-impl-base, analysis-api-standalone-fir → always @KaImplementationDetail. analysis-api-standalone-fir additionally exempts the org.jetbrains.kotlin.idea.references package through an isExempt override — that package is a public surface so its declarations are never flagged and never reach this skill.
• low-level-api-fir → @KaImplementationDetail for declarations in org.jetbrains.kotlin.analysis.low.level.api.fir.api (and subpackages); @LLFirInternals for everything else.

The set of annotations the test treats as already-marked (so they're never flagged) lives in AnalysisApiNonPublicMarkers: @KaImplementationDetail, @KaExperimentalApi, @KaPlatformInterface, @KaNonPublicApi, @KaIdeApi, @LLFirInternals. The test also skips internal/private declarations, annotation class declarations annotated with @RequiresOptIn, and declarations carrying override. None of those reach this skill.

The skill then refines the test's suggestion based on actual external usage. The rules differ slightly per module because of how sub-modules see each other:

In every implementation module, src/ and the test source sets are separate Kotlin modules — an internal declaration in src/ is not visible from tests/ or testFixtures/. That's why "used in own tests" is enough to disqualify a declaration from being internal. Only low-level-api-fir has its own opt-in marker (@LLFirInternals) for "test-accessible LL-FIR-internal" declarations; the other modules don't have a similar marker because their implementations don't go that deep, and @KaImplementationDetail is the catch-all for cross-sub-module visibility there.

The skill never adds annotations to declarations the codebase test didn't already touch — Phase 5 just builds and reports any remaining errors for manual review.

Phase 1: Run the codebase test in auto-apply mode

Replace any manual scan. The test discovers and annotates one violating file per run.

Step 1: Invoke the test with auto-apply enabled

./gradlew <gradle-task> \
    -Pkotlin.analysis.codebaseTest.internalApi.updateSourceCode=true \
    -Pkotlin.test.instrumentation.disable.inputs.check=true

• kotlin.analysis.codebaseTest.internalApi.updateSourceCode=true flips the abstract test into write-back mode: it writes the suggested fix to the violating source file, then throws to stop iteration.
• kotlin.test.instrumentation.disable.inputs.check=true disables the test-input security manager so the test JVM is allowed to write to source files.

Step 2: Interpret the outcome

• Test passes (BUILD SUCCESSFUL): every public declaration in <module>/src/ is already marked correctly. Skip to Phase 5 to perform a final build check.
• Test fails with "Auto-applied N marker annotation(s) to <File>.kt. ...": exactly one source file under <module>/src/ was modified on disk. The next phases work on that file.

If the test fails with a different message (compile error, security exception, etc.), stop and report the error to the user — the skill cannot make sense of unrelated failures.

Step 3: Identify the modified file

Use git diff --name-only (filtered to files under <module>/src/):

git diff --name-only -- '<module>/src/'

If multiple files are reported, prefer the one the test message named (the message contains the file's basename). Other files in the diff are likely the user's pre-existing edits — don't touch them.

Phase 2: Diff, downgrade, upgrade

For the modified file from Phase 1.

Step 1: Extract the newly added annotations

The test only inserts lines of the form <indent>@<MarkerName> directly above a declaration. Use git diff <file> (or mcp__idea__read_file on <file> and on the HEAD version via git show HEAD:<file>) to extract, for each insertion:

• the declaration the annotation precedes (kind, name, FQN);
• the inserted annotation — @KaImplementationDetail or @LLFirInternals.

Step 2: Classify each declaration's usages

For each newly marked declaration, determine where it is referenced besides its own src/:

• <module>/tests/, <module>/testFixtures/, <module>/test/ count as own tests.
• Ignore <module>/testData/: those are data files, not Kotlin sources, and can mention internal class names without it being a real usage.
• Anything else (other modules' src//tests/, the IntelliJ repository) counts as outside the module.

Tools to run the search:

• Within the Kotlin project: use mcp__idea__search_text (preferred for exact names) or mcp__idea__search_regex, with the paths parameter to scope the search. To distinguish own-tests from outside-the-module hits, run two queries (or read each result's path). For example, for a declaration in analysis/low-level-api-fir/, an "outside" search is:

  paths: ["!analysis/low-level-api-fir/**"]
  

  …and an "own tests" search is:

  paths: ["analysis/low-level-api-fir/tests/**", "analysis/low-level-api-fir/testFixtures/**"]
  

• Within the IntelliJ repository: the IntelliJ repo is a separate project, so JetBrains MCP cannot search it. Use the standard Grep tool against --intellij=<path>. Anything that hits in the IntelliJ repo counts as outside the module. If the path doesn't exist, notify the user but don't abort — proceed with Kotlin-repo results only.

Reducing false positives:

• For declarations with common names (create, get, resolve), search for the qualified name or a distinctive usage pattern (e.g., ClassName.methodName, import ...ClassName).
• When a hit is ambiguous, read the usage site to confirm it references this specific declaration.
• Classifier names (classes/interfaces/objects) are usually distinctive enough on their own.

Step 3: Apply the per-declaration decision

Apply edits with mcp__idea__apply_patch. Import housekeeping: when removing or replacing an annotation, also remove the corresponding import if no other declaration in the file still uses it. When adding @KaImplementationDetail, ensure import org.jetbrains.kotlin.analysis.api.KaImplementationDetail is present.

Companion-object exception. A companion object's marker must match its outer classifier's final marker. The companion is reached through the outer class (Outer.member → Outer.Companion.member), so callers who can opt into the outer must also reach the companion. Skip the usage analysis for companion objects in the diff entirely; instead, decide the outer first using the table above, then sync the companion:

• Outer kept as @KaImplementationDetail → companion stays @KaImplementationDetail.
• Outer kept as @LLFirInternals → companion stays @LLFirInternals.
• Outer upgraded to @KaImplementationDetail → upgrade the companion the same way (replace @LLFirInternals with @KaImplementationDetail, swap imports).
• Outer downgraded to internal → drop the companion's annotation (Step 4 below).

Step 4: Downgrading nested classifiers

If the same diff includes a top-level classifier and nested classifiers within it, and the top-level was downgraded to internal, the nested classifiers don't need their own marker — Kotlin's internal visibility transitively covers them. For each nested classifier in the diff under that newly-internal parent: drop the inserted annotation (and any redundant import), without adding internal.

The skill does not need to handle override declarations specially: the codebase test's isViolation filters them out before they reach the diff (see AbstractAnalysisApiInternalApiTest.isViolation).

Phase 3: Verify

Run JetBrains MCP get_file_problems with errorsOnly=false on the modified file. Fix any warnings or errors related to the changes (missing imports, opt-in requirements introduced by the new annotations, etc.).

Phase 4: Loop

Re-run Phase 1 Step 1 with the same flags. There are three outcomes:

• Test passes → proceed to Phase 5.
• Test fails on the same file you just processed → something went wrong (the downgrade/upgrade may have re-introduced a violation, or the file still has unmarked declarations). Stop and report to the user.
• Test fails on a new file → return to Phase 2 with that file.

Phase 5: Build and report

Run a normal compilation of the module:

./gradlew :analysis:<module>:compileKotlin -q

If the build succeeds, proceed to Phase 6.

If the build fails, stop and present the errors verbatim to the user for manual review. The skill does not auto-fix build errors. Common failure modes the user will need to resolve:

• "internal declaration exposed through public API" — a declaration the skill downgraded to internal is referenced in the signature of a public declaration in the same module. The user typically resolves this by switching the exposed declaration from internal to @KaImplementationDetail.
• OPT_IN_USAGE_ERROR at use sites — a callsite of a newly annotated declaration needs an @OptIn annotation, a module-level optIn compiler option, or its own marker annotation. These can also be triggered by previously unannotated declarations the test just marked.
• Unresolved imports — rare, but possible if the skill's import housekeeping in Phase 2 missed a case.

Auto-fixing any of these from the diff alone risks masking real problems (e.g., upgrading internal to @KaImplementationDetail everywhere on exposure would defeat the point of distinguishing the two), so this is left for manual review.

Phase 6: Final summary

Present a per-classification breakdown:

• Declarations marked internal (Phase 2 downgrades).
• Declarations kept as @KaImplementationDetail (test's suggestion confirmed).
• Declarations kept as @LLFirInternals (own-tests-only access; no usages outside analysis/low-level-api-fir/).
• Declarations upgraded from @LLFirInternals to @KaImplementationDetail (Phase 2 upgrades).
• Any compilation errors flagged in Phase 5 for the user to resolve manually.