fix(kotlin): link a typed-receiver call to an extension declared in a package

[bompus]

In Kotlin, a call on a typed receiver now links to an extension function declared in a package, such as value.shout() or the infix a join b.

On JetBrains Exposed (2155404) this adds 1,020 call links and removes none; node sets are identical. A sample of 16 of the new links, and the ones whose owner is a standard type (Sequence, Set, Triple, Iterable, String), were checked against the source and all point at the right extension.

Cause

An extension function is stored as Foo::shout (receiver as written, no package) while the class it extends is pkg::Foo. The typed-receiver lookup found members by {class qualified name}::{name}, so an extension in a packaged file was never found. The same extension did link when the file had no package line, or through an implicit receiver.

Change

• kotlin_receiver.rs: the existing candidate scan for extensions is now kotlin_extension_member, called at the end of kotlin_receiver_member as before.
• method_call.rs: when the inferable-receiver path finds no member on the receiver's class and the language is Kotlin, it falls back to kotlin_extension_member. A real member still wins.
• New __tests__/kotlin-extension-call-typed-receiver.test.ts: constructor-typed and parameter-typed receivers, an infix call, member-wins, a different receiver type, and an unrelated extension.
• __tests__/kotlin-infix-calls.test.ts: the "project numeric extension" case pinned the gap ([]); it now expects Int::and, the extension on a project class declared in a package.

Checks

• Kernel golden dumps: unchanged.
• Full vitest run before the pinned-test update: 8,913 passed, the one pinned case failed; it passes after the expectation change.
• README rows checked: added a bullet to the "About this fork" Kotlin list; the upstream merge point and the benchmark tables are unaffected (no timing change). CHANGELOG entry added under Unreleased Fixes.

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Summary by cubic

Links Kotlin calls on typed receivers to extension functions declared in a package, such as value.shout() or the infix a join b where shout/join extend a class under package demo. Previously such calls linked only when the extension's file had no package line, so typical Kotlin projects got no edge.

• When the receiver's class has no member of that name, the resolver now falls back to the one visible extension whose receiver accepts the type; a real member still wins.
• On JetBrains Exposed this adds 1,020 call links and removes none.
• Adds a test covering constructor- and parameter-typed receivers, an infix call, member-wins precedence, a different receiver type, and an unrelated extension, and updates the "project numeric extension" infix case to expect Int::and.

^{Written for commit da70ad6. Summary will update on new commits.}

Summary by CodeRabbit

• New Features
  • Kotlin calls on typed receivers now link to matching package-declared extension functions, including infix extensions and extensions declared in another file of the same package.
  • Class members take precedence when they share a name with an extension. Ambiguous extension matches are not linked.
  • JetBrains Exposed analysis now reports 1,020 additional call links, with none removed.

[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

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• Run ID: 266e3fd8-073a-4b62-9e01-0c8c690691c1

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📥 Commits

Reviewing files that changed from the base of the PR and between 66c7e71 and da70ad6.

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📒 Files selected for processing (6)

• CHANGELOG.md
• README.md
• __tests__/kotlin-extension-call-typed-receiver.test.ts
• __tests__/kotlin-infix-calls.test.ts
• codegraph-kernel/src/resolve/kotlin_receiver.rs
• codegraph-kernel/src/resolve/method_call.rs

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📝 Walkthrough

Walkthrough

Kotlin call resolution now checks package-declared extension functions when typed-receiver member lookup finds no matching class member. Tests cover typed and constructed receivers, infix calls, member precedence, and unmatched receiver types. The README and changelog describe the change.

Changes

Kotlin Extension Resolution

Layer / File(s)	Summary
Resolve Kotlin extensions codegraph-kernel/src/resolve/method_call.rs, codegraph-kernel/src/resolve/kotlin_receiver.rs	When Kotlin receiver-type member lookup finds no match, resolution checks compatible extension methods. It returns a candidate only when matching extensions share a qualified name and file path.
Validate and document extension calls __tests__/kotlin-extension-call-typed-receiver.test.ts, __tests__/kotlin-infix-calls.test.ts, CHANGELOG.md, README.md	Tests cover typed-receiver and infix extension calls, member precedence, and unmatched receiver types. Documentation describes the resolution behavior and reports 1,020 additional JetBrains Exposed call links with none removed.

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Priority: ➖ Normal

Merge Risk: ⚪ Minimal · up to da70a

No confirmed issue remains that should block merging after normal checks.

Pre-merge checks | 6

✅ Passed checks (6 passed)

Check name	Status	Explanation
Description Check		Check skipped - CodeRabbit’s high-level summary is enabled.
Title check		The title clearly and concisely describes the main change: Kotlin typed-receiver calls now link to package-declared extension functions.
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Suppressions Explained		The pull request adds no lint, type-check, compiler-diagnostic, or ignore directive. The changed Rust, TypeScript, and documentation lines contain no suppression such as #[allow(...)], `eslint-disab…
User-Visible Changes Documented		The diff changes Kotlin call-resolution behavior and tests only. It does not add, remove, or rename a CLI command or flag, MCP tool or argument, supported language/framework, agent target, or config k…

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