feat(gitea): der Commit-Status verlinkt endlich die Artefaktseite — repo-bezogen

Der letzte offene Punkt der Sitzung D („Gitea status links use the repo-scoped
URLs"). Beim Nachsehen war es kein Scoping-Problem, sondern ein fehlendes
Feature: `server.publicBaseUrl` ist als „used for all links posted to Gitea"
dokumentiert, der Executor postete aber `targetUrl = null` — es gab überhaupt
keinen Link. Jetzt zeigt der Status auf die Artefaktseite des Builds, also auf
die Logs, um die es geht. Ohne `publicBaseUrl` bleibt er null: ein relativer
Link in einem Gitea-Status wäre schlimmer als keiner, er löste gegen die Forge
auf.

Die Präfix-Regel wohnt jetzt an einer Stelle (`RepoLinks`), weil drei
dasselbe damit tun: die Seiten, die API-Antworten und diese Ziel-URLs — und
eine dreimal ausgeschriebene Regel driftet. Die Slice-Tests binden die echte
Komponente per @Import ein, statt die Regel im Test nachzubauen.

Ein neuer Test (mit publicBaseUrl trägt der Status die Artefaktseite; die
vorhandenen Tests halten fest, dass ohne sie weiterhin null gepostet wird).
499 Tests grün, ktlint sauber. Plan und Architektur-Skill nachgezogen.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/main/kotlin/de/hoennig/werkator/build/BuildExecutor.kt

@@ -5,6 +5,7 @@ import de.hoennig.werkator.config.BuildDefinition
 import de.hoennig.werkator.config.ConfigLoader
 import de.hoennig.werkator.gitea.GiteaClient
 import de.hoennig.werkator.repo.RepoContext
+import de.hoennig.werkator.repo.RepoLinks
 import org.slf4j.LoggerFactory
 import org.springframework.context.ApplicationEventPublisher
 import org.springframework.context.event.ContextClosedEvent
@@ -36,6 +37,7 @@ import kotlin.concurrent.thread
 @Service
 class BuildExecutor(
     private val configLoader: ConfigLoader,
+    private val repoLinks: RepoLinks,
     private val giteaClient: GiteaClient,
     private val buildRunner: BuildRunner,
     private val workspaces: BranchWorkspaces,
@@ -397,7 +399,7 @@ class BuildExecutor(
                 sha = build.runningBuild.commit,
                 status = status,
                 description = description(status, duration),
-                targetUrl = null,
+                targetUrl = targetUrlOf(build),
                 workingDir = build.repo.workingDir,
                 // from the primary config, not the worktree: statusContext is pinned, so a
                 // branch cannot report under a check name it was not given
@@ -408,6 +410,25 @@ class BuildExecutor(
         }
     }
 
+    /**
+     * The artifact page of this build, so a commit status in the forge leads to the
+     * logs it is about — that is what `server.publicBaseUrl` is documented for, and
+     * until now nothing posted a link at all. Repository-scoped (ADR 0009): with
+     * several served repositories the unscoped path would resolve against whichever
+     * one the instance serves by default, which is the wrong build's page.
+     */
+    private fun targetUrlOf(build: ActiveBuild): String? =
+        try {
+            repoLinks.buildUrl(
+                repo = build.repo,
+                publicBaseUrl = configLoader.load(build.repo.workingDir).server.publicBaseUrl,
+                artifactKey = build.runningBuild.artifactKey,
+            )
+        } catch (e: Exception) {
+            log.warn("could not build the status target URL of {}: {}", build.runningBuild.branch, e.message)
+            null
+        }
+
     /** The build's own Gitea status context, empty when it uses the repository-wide one. */
     private fun statusContextOf(build: ActiveBuild): String =
         try {

src/main/kotlin/de/hoennig/werkator/repo/RepoLinks.kt

@@ -0,0 +1,37 @@
+package de.hoennig.werkator.repo
+
+import org.springframework.stereotype.Component
+
+/**
+ * The path prefix a link to a repository carries (ADR 0009). One place knows the
+ * rule, because three do the same thing with it: the pages, the API answers, and
+ * the target URLs posted to Gitea — and a rule spelled out three times is a rule
+ * that drifts.
+ *
+ * It follows the NUMBER of served repositories, not the route a request arrived
+ * through: with one repository an installation keeps the URLs it always had, with
+ * several every link names its repository.
+ */
+@Component
+class RepoLinks(
+    private val registry: RepoRegistry,
+) {
+    fun base(repo: RepoContext): String = if (registry.all().size > 1) "/repos/${repo.name}" else ""
+
+    fun apiBase(repo: RepoContext): String = if (registry.all().size > 1) "/api/repos/${repo.name}" else "/api"
+
+    /**
+     * The absolute artifact-page URL of a build, for links Werkator posts elsewhere
+     * (`server.publicBaseUrl`). Null without a public base URL: a relative link in a
+     * Gitea status is worse than none — it would resolve against the forge.
+     */
+    fun buildUrl(
+        repo: RepoContext,
+        publicBaseUrl: String,
+        artifactKey: String,
+    ): String? {
+        val root = publicBaseUrl.trim().trimEnd('/')
+        if (root.isEmpty()) return null
+        return "$root${base(repo)}/builds/$artifactKey"
+    }
+}

src/main/kotlin/de/hoennig/werkator/server/BuildsApiController.kt

@@ -6,6 +6,7 @@ import de.hoennig.werkator.build.BuildStatus
 import de.hoennig.werkator.config.BuildDefinition
 import de.hoennig.werkator.git.GitService
 import de.hoennig.werkator.repo.RepoContext
+import de.hoennig.werkator.repo.RepoLinks
 import de.hoennig.werkator.repo.RepoRegistry
 import org.springframework.http.HttpStatus
 import org.springframework.http.ResponseEntity
@@ -37,6 +38,7 @@ class BuildsApiController(
     private val gitService: GitService,
     private val branchListing: BranchListing,
     private val registry: RepoRegistry,
+    private val repoLinks: RepoLinks,
 ) {
     /**
      * Every route exists twice: repository-scoped (`/api/repos/<name>/…`) and unscoped.
@@ -52,7 +54,7 @@ class BuildsApiController(
         results.latestGreenFor(result.name)?.artifactKey == result.artifactKey
 
     /** The prefix the permanent links in the answers carry; empty with one served repository. */
-    private fun uiBase(repo: RepoContext): String = if (registry.all().size > 1) "/repos/${repo.name}" else ""
+    private fun uiBase(repo: RepoContext): String = repoLinks.base(repo)
 
     /** An unknown repository name answers like every other miss of this API: 404 with `error`. */
     @ExceptionHandler(UnknownRepositoryException::class)

src/main/kotlin/de/hoennig/werkator/server/UiController.kt

@@ -8,6 +8,7 @@ import de.hoennig.werkator.config.ConfigLoader
 import de.hoennig.werkator.git.GitService
 import de.hoennig.werkator.metrics.SystemMetricsCollector
 import de.hoennig.werkator.repo.RepoContext
+import de.hoennig.werkator.repo.RepoLinks
 import de.hoennig.werkator.repo.RepoRegistry
 import jakarta.servlet.http.HttpServletRequest
 import org.springframework.beans.factory.ObjectProvider
@@ -43,6 +44,7 @@ class UiController(
     private val branchPermalinks: BranchPermalinks,
     private val buildProperties: ObjectProvider<BuildProperties>,
     private val registry: RepoRegistry,
+    private val repoLinks: RepoLinks,
 ) {
     /**
      * Every page exists twice, like the API (ADR 0009): repository-scoped under
@@ -272,9 +274,9 @@ class UiController(
      * repository the installation keeps its existing URLs (the session-D acceptance
      * criterion), with several every link names its repository.
      */
-    private fun uiBase(repo: RepoContext): String = if (registry.all().size > 1) "/repos/${repo.name}" else ""
+    private fun uiBase(repo: RepoContext): String = repoLinks.base(repo)
 
-    private fun apiBase(repo: RepoContext): String = if (registry.all().size > 1) "/api/repos/${repo.name}" else "/api"
+    private fun apiBase(repo: RepoContext): String = repoLinks.apiBase(repo)
 
     /** Adds the attributes every page needs and returns the Gitea link helper for row building. */
     private fun baseModel(