Add API Reference

Add a new kotlinx API reference

This skill publishes a library's Dokka-generated API reference at https://kotlinlang.org/api/<id>/, built and indexed by the same TeamCity pipeline that produces the coroutines, serialization, datetime and io references.

Everything is wired through the TeamCity Kotlin DSL under .teamcity/. A reference is a fixed set of pieces, all mirroring an existing library — there is no new infrastructure to write, only new config objects plus a couple of site-side links.

The reference implementation is kotlinx-datetime; mirror it. Datetime is the right model for any library whose Dokka output lives under a core/ module (core/build/dokka/html, core/dokka-templates). For a single-module library whose Dokka output is at the repo root, mirror kotlinx-io instead (build/dokka/html, root dokka-templates).

Follow .ai/guidelines.md at all times (required by CLAUDE.md).

When to use

The user wants a Kotlin/* library's API reference served on kotlinlang.org/api alongside the other kotlinx libraries — for example, migrating it off a temporary GitHub Pages site.

Inputs to gather first

Ask the user for these (defaults shown are the kotlinx.collections.immutable worked example). Derive the casing variants from the base name.

Steps — apply these edits

Make the edits in this order. Each is anchored to an existing pattern; append the new entry alongside the others rather than reformatting the file. Replace the <…> placeholders with the gathered inputs; the worked example below shows every value filled in.

1. Add the BuildParams consts + sitemap entry

File: .teamcity/BuildParams.kt

Add four consts inside object BuildParams, after the last library block (currently KOTLINX_IO_*):

const val <PREFIX>_RELEASE_TAG = "<release tag>"
const val <PREFIX>_RELEASE_LABEL = "<release label>"
const val <PREFIX>_ID = "<api id>"
const val <PREFIX>_TITLE = <PREFIX>_ID

Then add one line to the API_URLS list (drives the sitemap index), next to the other api/... entries:

"api/$<PREFIX>_ID",

2. Add the VCS root

New file: .teamcity/references/vcsRoots/<Base>.kt.

Building from a tag (e.g. v0.5.0 — the usual case for a stable release). Use the full ref via the VCS.tag(...) helper and a tag-only branchSpec. Do not pass a bare tag name to branch with a +:refs/heads/(*) spec — TeamCity expands the short name to refs/heads/<tag>, which doesn't exist, and fails with "Cannot find revision of the default branch".

package references.vcsRoots

import BuildParams.<PREFIX>_RELEASE_TAG
import common.extensions.VCS
import jetbrains.buildServer.configs.kotlin.vcs.GitVcsRoot

object <Base> : GitVcsRoot({
  name = "<api id> vcs root"
  url = "<git SSH URL>"
  branch = VCS.tag(<PREFIX>_RELEASE_TAG)   // refs/tags/<release tag>
  branchSpec = "+:refs/tags/*"
  useTagsAsBranches = true
  authMethod = uploadedKey {
    uploadedKey = "teamcity"
  }
})

Building from a branch (e.g. master, latest-release — the kotlinx-io / datetime style). Use the branch name directly with the heads+tags spec:

  branch = <PREFIX>_RELEASE_TAG            // e.g. "master" or "latest-release"
  branchSpec = """
    +:refs/heads/(*)
    +:refs/tags/(*)
  """.trimIndent()
  useTagsAsBranches = true

3. Add the three build objects

New directory: .teamcity/references/builds/kotlinx/<segment>/ with three files.

<Base>PrepareDokkaTemplates.kt — verbatim from datetime with new ids:

package references.builds.kotlinx.<segment>

import BuildParams.<PREFIX>_ID
import BuildParams.<PREFIX>_TITLE
import jetbrains.buildServer.configs.kotlin.BuildType
import references.templates.PrepareDokkaTemplate

object <Base>PrepareDokkaTemplates : BuildType({
    name = "$<PREFIX>_ID templates"
    description = "Build dokka templates for <human name>"

    templates(PrepareDokkaTemplate)

    params {
        param("env.ALGOLIA_INDEX_NAME", <PREFIX>_ID)
        param("env.API_REFERENCE_NAME", <PREFIX>_TITLE)
    }
})

<Base>BuildApiReference.kt — core/-module shape (datetime). Drop the pagesRoot private const, the stepBuildHtml task, and the dependsOnDokkaTemplate dir to match a root-module lib (io) if applicable:

package references.builds.kotlinx.<segment>

import BuildParams.<PREFIX>_ID
import BuildParams.<PREFIX>_RELEASE_LABEL
import references.BuildApiPages
import references.dependsOnDokkaTemplate
import references.scriptBuildHtml
import references.vcsRoots.<Base>

private const val DOKKA_HTML_RESULT = "<dokka html output>"

object <Base>BuildApiReference : BuildApiPages(
    apiId = <PREFIX>_ID,
    releaseTag = <PREFIX>_RELEASE_LABEL,
    pagesRoot = DOKKA_HTML_RESULT,
    stepBuildHtml = {
        scriptBuildHtml { tasks = "<dokka gradle task>" }
    },
    init = {
        vcs {
            root(<Base>)
        }
        dependencies {
            dependsOnDokkaTemplate(<Base>PrepareDokkaTemplates, "<dokka templates dir>")
        }
    })

If the library's gradle.properties uses a non-standard version key (datetime overrides stepDropSnapshot to strip versionSuffix=SNAPSHOT), add a matching stepDropSnapshot = { … } override — see datetime. The default handles a plain version=… property.

<Base>BuildSearchIndex.kt — verbatim from datetime with new ids:

package references.builds.kotlinx.<segment>

import BuildParams.<PREFIX>_ID
import templates.TemplateSearchIndex

object <Base>BuildSearchIndex : TemplateSearchIndex({
    name = "$<PREFIX>_ID search"
    description = "Build search index for <human name>"

    params {
        param("env.ALGOLIA_INDEX_NAME", "$<PREFIX>_ID")
    }

    dependencies {
        dependency(<Base>BuildApiReference) {
            snapshot {}
            artifacts {
                artifactRules = """
                    pages.zip!** => dist/api/$<PREFIX>_ID/
                """.trimIndent()
                cleanDestination = true
            }
        }
    }
})

4. Register the builds + VCS root in the project

File: .teamcity/references/BuildApiReferencesProject.kt

Add the imports (alongside the existing references.builds.kotlinx.* and references.vcsRoots.* imports — the latter is a wildcard, so no vcsRoot import is needed):

import references.builds.kotlinx.<segment>.<Base>BuildApiReference
import references.builds.kotlinx.<segment>.<Base>BuildSearchIndex
import references.builds.kotlinx.<segment>.<Base>PrepareDokkaTemplates

Inside the Project({ … }) body, add the three build types next to the others:

buildType(<Base>BuildApiReference)
buildType(<Base>BuildSearchIndex)
buildType(<Base>PrepareDokkaTemplates)

…and register the VCS root next to the other vcsRoot(...) calls:

vcsRoot(<Base>)

5. Add the navigation link

File: docs/kr.tree

Inside the <toc-element toc-title="API reference"> block, add a link next to the other library entries:

<toc-element toc-title="<TOC title>" href="https://kotlinlang.org/api/<api id>/"/>

6. Add the production navigation test

File: test/production/api-navigation.spec.ts

Add a test mirroring the existing ones, using the TOC title as the button text and the /api/<id>/ slug:

test('Click on "<TOC title short>" button should open the related page', async ({ page }) => {
    const button = await hoverOverApiElement(page, '<TOC title short>');
    await expect(button).toBeVisible();
    await button.click();
    expect(page.url()).toContain('/api/<api id>/');
});

<TOC title short> is the leading text of the TOC title that hoverOverApiElement matches (e.g. Immutable collections).

Worked example — kotlinx.collections.immutable

The exact change for KTL-4524. Inputs: base KotlinxCollectionsImmutable, segment collectionsImmutable, prefix KOTLINX_COLLECTIONS_IMMUTABLE, id kotlinx.collections.immutable, repo [email protected]:Kotlin/kotlinx.collections.immutable.git, tag v0.5.0, label 0.5.0, core/ module layout.

# .teamcity/BuildParams.kt  (after the KOTLINX_IO_* block)
+  const val KOTLINX_COLLECTIONS_IMMUTABLE_RELEASE_TAG = "v0.5.0"
+  const val KOTLINX_COLLECTIONS_IMMUTABLE_RELEASE_LABEL = "0.5.0"
+  const val KOTLINX_COLLECTIONS_IMMUTABLE_ID = "kotlinx.collections.immutable"
+  const val KOTLINX_COLLECTIONS_IMMUTABLE_TITLE = KOTLINX_COLLECTIONS_IMMUTABLE_ID

# .teamcity/BuildParams.kt  (in API_URLS)
     "api/$KOTLINX_IO_ID",
     "api/$KOTLINX_METADATA_ID",
+    "api/$KOTLINX_COLLECTIONS_IMMUTABLE_ID",
     "api/${KGP_REFERENCE.urlPart}",

// .teamcity/references/vcsRoots/KotlinxCollectionsImmutable.kt  (new)
package references.vcsRoots

import BuildParams.KOTLINX_COLLECTIONS_IMMUTABLE_RELEASE_TAG
import common.extensions.VCS
import jetbrains.buildServer.configs.kotlin.vcs.GitVcsRoot

object KotlinxCollectionsImmutable : GitVcsRoot({
  name = "kotlinx.collections.immutable vcs root"
  url = "[email protected]:Kotlin/kotlinx.collections.immutable.git"
  // Pinned to the stable release tag (full ref so the short name isn't resolved as a head).
  branch = VCS.tag(KOTLINX_COLLECTIONS_IMMUTABLE_RELEASE_TAG)
  branchSpec = "+:refs/tags/*"
  useTagsAsBranches = true
  authMethod = uploadedKey {
    uploadedKey = "teamcity"
  }
})

// .teamcity/references/builds/kotlinx/collectionsImmutable/KotlinxCollectionsImmutablePrepareDokkaTemplates.kt  (new)
package references.builds.kotlinx.collectionsImmutable

import BuildParams.KOTLINX_COLLECTIONS_IMMUTABLE_ID
import BuildParams.KOTLINX_COLLECTIONS_IMMUTABLE_TITLE
import jetbrains.buildServer.configs.kotlin.BuildType
import references.templates.PrepareDokkaTemplate

object KotlinxCollectionsImmutablePrepareDokkaTemplates : BuildType({
    name = "$KOTLINX_COLLECTIONS_IMMUTABLE_ID templates"
    description = "Build dokka templates for Kotlinx Collections Immutable"

    templates(PrepareDokkaTemplate)

    params {
        param("env.ALGOLIA_INDEX_NAME", KOTLINX_COLLECTIONS_IMMUTABLE_ID)
        param("env.API_REFERENCE_NAME", KOTLINX_COLLECTIONS_IMMUTABLE_TITLE)
    }
})

// .teamcity/references/builds/kotlinx/collectionsImmutable/KotlinxCollectionsImmutableBuildApiReference.kt  (new)
package references.builds.kotlinx.collectionsImmutable

import BuildParams.KOTLINX_COLLECTIONS_IMMUTABLE_ID
import BuildParams.KOTLINX_COLLECTIONS_IMMUTABLE_RELEASE_LABEL
import references.BuildApiPages
import references.dependsOnDokkaTemplate
import references.scriptBuildHtml
import references.scriptDropSnapshot
import references.vcsRoots.KotlinxCollectionsImmutable

private const val DOKKA_HTML_RESULT = "core/build/dokka/html"

object KotlinxCollectionsImmutableBuildApiReference : BuildApiPages(
    apiId = KOTLINX_COLLECTIONS_IMMUTABLE_ID,
    releaseTag = KOTLINX_COLLECTIONS_IMMUTABLE_RELEASE_LABEL,
    pagesRoot = DOKKA_HTML_RESULT,
    // gradle.properties has `version=0.5.0` + a separate `versionSuffix=SNAPSHOT`; strip the
    // suffix (the default drop-snapshot only rewrites `version=`). Same as datetime.
    stepDropSnapshot = {
        scriptDropSnapshot {
            // language=bash
            scriptContent = """
                #!/bin/bash
                sed -i -E "s/versionSuffix=SNAPSHOT//gi" ./gradle.properties
            """.trimIndent()
        }
    },
    stepBuildHtml = {
        scriptBuildHtml { tasks = ":kotlinx-collections-immutable:dokkaGenerate" }
    },
    init = {
        vcs {
            root(KotlinxCollectionsImmutable)
        }
        dependencies {
            dependsOnDokkaTemplate(KotlinxCollectionsImmutablePrepareDokkaTemplates, "core/dokka-templates")
        }
    })

// .teamcity/references/builds/kotlinx/collectionsImmutable/KotlinxCollectionsImmutableBuildSearchIndex.kt  (new)
package references.builds.kotlinx.collectionsImmutable

import BuildParams.KOTLINX_COLLECTIONS_IMMUTABLE_ID
import templates.TemplateSearchIndex

object KotlinxCollectionsImmutableBuildSearchIndex : TemplateSearchIndex({
    name = "$KOTLINX_COLLECTIONS_IMMUTABLE_ID search"
    description = "Build search index for Kotlinx Collections Immutable"

    params {
        param("env.ALGOLIA_INDEX_NAME", "$KOTLINX_COLLECTIONS_IMMUTABLE_ID")
    }

    dependencies {
        dependency(KotlinxCollectionsImmutableBuildApiReference) {
            snapshot {}
            artifacts {
                artifactRules = """
                    pages.zip!** => dist/api/$KOTLINX_COLLECTIONS_IMMUTABLE_ID/
                """.trimIndent()
                cleanDestination = true
            }
        }
    }
})

# .teamcity/references/BuildApiReferencesProject.kt  (imports)
+import references.builds.kotlinx.collectionsImmutable.KotlinxCollectionsImmutableBuildApiReference
+import references.builds.kotlinx.collectionsImmutable.KotlinxCollectionsImmutableBuildSearchIndex
+import references.builds.kotlinx.collectionsImmutable.KotlinxCollectionsImmutablePrepareDokkaTemplates

# .teamcity/references/BuildApiReferencesProject.kt  (Project body)
+    buildType(KotlinxCollectionsImmutableBuildApiReference)
+    buildType(KotlinxCollectionsImmutableBuildSearchIndex)
+    buildType(KotlinxCollectionsImmutablePrepareDokkaTemplates)
...
+    vcsRoot(KotlinxCollectionsImmutable)

# docs/kr.tree  (inside <toc-element toc-title="API reference">)
     <toc-element toc-title="Date and time (kotlinx-datetime)" href="https://kotlinlang.org/api/kotlinx-datetime/"/>
+    <toc-element toc-title="Immutable collections (kotlinx.collections.immutable)" href="https://kotlinlang.org/api/kotlinx.collections.immutable/"/>
     <toc-element toc-title="JVM Metadata (kotlinx-metadata-jvm)" href="https://kotlinlang.org/api/kotlinx-metadata-jvm/"/>

// test/production/api-navigation.spec.ts  (new test next to the others)
test('Click on "Immutable collections" button should open the related page', async ({ page }) => {
    const immutableButton = await hoverOverApiElement(page, 'Immutable collections');
    await expect(immutableButton).toBeVisible();
    await immutableButton.click();
    expect(page.url()).toContain('/api/kotlinx.collections.immutable/');
});

Pre-conditions to confirm against the source repo

Before relying on the datetime defaults, check these against Kotlin/kotlinx.collections.immutable at the chosen tag (the issue reporter offered to share the build details on request):

• The v0.5.0 tag exists. If the stable release isn't tagged yet, build from latest-release (datetime-style) or master (io-style) and update the label accordingly.
• The Dokka Gradle task path — :kotlinx-collections-immutable:dokkaGenerate vs :core:dokkaGenerate vs a root :dokkaGenerate. Verify in the repo's settings.gradle.kts / core/build.gradle.kts.
• The Dokka HTML output path (core/build/dokka/html) and the templates dir (core/dokka-templates) match where core/build.gradle.kts writes/expects them.
• The version property in gradle.properties — if it's not a plain version=…, add a stepDropSnapshot override (see datetime's versionSuffix=SNAPSHOT).
• The id/slug matches the desired public URL and the repo naming (immutable uses the dotted kotlinx.collections.immutable, like coroutines/serialization).

Verify

• Compile/validate the TeamCity DSL so the new objects, imports and registration are valid Kotlin: cd .teamcity && mvn -q teamcity-configs:generate (or the repo's configured DSL check). It should generate without errors and emit configs for the three new build types.
• Confirm docs/kr.tree is still valid XML and the new entry sits under "API reference".
• The change should touch only: .teamcity/BuildParams.kt, .teamcity/references/BuildApiReferencesProject.kt, the new vcsRoots/<Base>.kt, the three new builds/kotlinx/<segment>/*.kt files, docs/kr.tree, and test/production/api-navigation.spec.ts — nothing else.
• After the build runs on TeamCity, <Base>BuildApiReference → <Base>BuildSearchIndex produce and index /api/<id>/; the new production navigation test should pass against the deployed site.