Fix auto indexer resolution to always mean PHP (#77)

Root cause: HealthChecker and IndexerResolver probed for the Pagefind
binary when indexer was set to 'auto', reporting binary as active.
This contradicts the design rule that auto always means PHP. The binary
pipeline requires explicit 'indexer: binary' configuration.

Fixes: HealthChecker.check() now reads the configured indexer setting
instead of probing binary availability. IndexerResolver.resolve()
returns 'php' for auto without binary probe (dead code but corrected
for consistency). Tests updated to assert the correct auto=php behavior.

Author: jeremyandrews

CHANGELOG.md

@@ -6,7 +6,8 @@ This project uses [Semantic Versioning](https://semver.org/). Major versions are
 
 ## [Unreleased]
 
-_No changes yet._
+### Fixed
+- **`auto` indexer now always means PHP on all code paths.** `HealthChecker::check()` now reads the configured `indexer` setting instead of probing binary availability when reporting `indexer_active` — it previously reported `binary` whenever the Pagefind binary was present on disk, even when the setting was `auto` or `php`. `IndexerResolver::resolve()` likewise returns `php` for `auto` without probing the binary. The binary pipeline requires explicit `indexer: binary` configuration.
 
 ## [1.0.0-rc1] - 2026-05-11
 

src/Health/HealthChecker.php

@@ -54,11 +54,11 @@ public function check(): array
             $status = 'degraded';
         }
 
-        $indexerActive = $binaryStatus['available'] ? 'binary' : 'php';
-        $upgradeMessage = $binaryStatus['available']
-            ? null
-            : 'Pagefind binary not found. Using PHP indexer (slower, 14 Snowball languages vs 33+). '
-              . 'For faster indexing: npm install -g pagefind';
+        $configuredIndexer = $this->config->indexer ?? 'auto';
+        $indexerActive = ($configuredIndexer === 'binary' && $binaryStatus['available']) ? 'binary' : 'php';
+        $upgradeMessage = ($configuredIndexer === 'binary' && !$binaryStatus['available'])
+            ? 'Pagefind binary not found. Set indexer to "php" or install Pagefind: npm install -g pagefind'
+            : null;
 
         return [
             'status' => $status,
@@ -68,7 +68,7 @@ public function check(): array
             'wasm_available' => false,
             'index_exists' => $indexExists,
             'indexer_active' => $indexerActive,
-            'indexer_upgrade_available' => !$binaryStatus['available'],
+            'indexer_upgrade_available' => ($configuredIndexer === 'binary' && !$binaryStatus['available']),
             'indexer_upgrade_message' => $upgradeMessage,
             'pagefind' => [
                 'available' => $binaryStatus['available'],

src/Index/IndexerResolver.php

@@ -10,9 +10,13 @@
 /**
  * Resolves which indexer backend to use and emits notice-level log messages.
  *
- * Encapsulates auto-detection and fallback logic so every adapter emits
- * the same structured messages. Adapters call resolve() and act on the
- * returned string ('php' or 'binary'). All logging is handled here.
+ * Encapsulates indexer selection logic so every adapter emits the same
+ * structured messages. Adapters call resolve() and act on the returned
+ * string ('php' or 'binary'). All logging is handled here.
+ *
+ * Design rule: 'auto' always means PHP. Binary pipeline requires explicit
+ * 'indexer: binary' configuration. If binary is unavailable when 'binary'
+ * is configured, falls back to PHP with a log notice.
  *
  * Log messages:
  *   - [scolta] Using PHP indexer.
@@ -54,16 +58,9 @@ public function resolve(string $effectiveIndexer): string
             return 'php';
         }
 
-        // 'auto' (or any unrecognised value): probe binary, fall back to PHP.
-        $path = $this->binary->resolve();
-        if ($path !== null) {
-            $this->logger->notice(
-                '[scolta] Using binary indexer (auto-detected): {binary}.',
-                ['binary' => $path],
-            );
-            return 'binary';
-        }
-        $this->logger->notice('[scolta] Using PHP indexer (auto: binary not available).');
+        // 'auto' (or any unrecognised value): always PHP.
+        // Binary pipeline requires explicit 'indexer: binary' configuration.
+        $this->logger->notice('[scolta] Using PHP indexer.');
         return 'php';
     }
 }

tests/Health/HealthCheckerTest.php

@@ -156,6 +156,45 @@ public function testIndexCheckVerifiesPagefindJs(): void
         $this->assertTrue($result2['index_exists']);
     }
 
+    // -------------------------------------------------------------------
+    // indexer_active reflects config, not binary availability
+    // -------------------------------------------------------------------
+
+    public function testIndexerActiveIsPhpWhenConfigIsAuto(): void
+    {
+        $config = ScoltaConfig::fromArray(['ai_api_key' => 'sk-test', 'indexer' => 'auto']);
+        $checker = new HealthChecker($config, $this->tempDir, null, null);
+
+        $result = $checker->check();
+
+        $this->assertSame('php', $result['indexer_active']);
+    }
+
+    public function testIndexerActiveIsPhpWhenConfigIsPhp(): void
+    {
+        $config = ScoltaConfig::fromArray(['ai_api_key' => 'sk-test', 'indexer' => 'php']);
+        $checker = new HealthChecker($config, $this->tempDir, null, null);
+
+        $result = $checker->check();
+
+        $this->assertSame('php', $result['indexer_active']);
+    }
+
+    public function testIndexerActiveIsBinaryWhenConfigIsBinaryAndBinaryAvailable(): void
+    {
+        // Create a fake binary so PagefindBinary reports available.
+        $tempBin = $this->tempDir . '/pagefind';
+        file_put_contents($tempBin, "#!/bin/sh\necho 'pagefind 1.5.0'");
+        chmod($tempBin, 0755);
+
+        $config = ScoltaConfig::fromArray(['ai_api_key' => 'sk-test', 'indexer' => 'binary']);
+        $checker = new HealthChecker($config, $this->tempDir, $tempBin, null);
+
+        $result = $checker->check();
+
+        $this->assertSame('binary', $result['indexer_active']);
+    }
+
     // -------------------------------------------------------------------
     // Helpers
     // -------------------------------------------------------------------

tests/Index/IndexerResolverTest.php

@@ -116,21 +116,31 @@ public function testBinaryModeWithMissingBinaryLogsFallback(): void
     }
 
     // -------------------------------------------------------------------
-    // 'auto' mode — binary available
+    // 'auto' mode — always PHP regardless of binary availability
     // -------------------------------------------------------------------
 
-    public function testAutoModeWithAvailableBinaryReturnsBinary(): void
+    public function testAutoModeReturnsPhp(): void
+    {
+        $logger = new IndexerResolverLogger();
+        $resolver = new IndexerResolver(new PagefindBinary(), $logger);
+
+        $result = $resolver->resolve('auto');
+
+        $this->assertSame('php', $result);
+    }
+
+    public function testAutoModeWithAvailableBinaryStillReturnsPhp(): void
     {
         $logger = new IndexerResolverLogger();
         $binary = new PagefindBinary(configuredPath: $this->fakeBinary);
         $resolver = new IndexerResolver($binary, $logger);
 
         $result = $resolver->resolve('auto');
 
-        $this->assertSame('binary', $result);
+        $this->assertSame('php', $result);
     }
 
-    public function testAutoModeWithAvailableBinaryLogsBinaryIndexer(): void
+    public function testAutoModeLogsUsingPhpIndexer(): void
     {
         $logger = new IndexerResolverLogger();
         $binary = new PagefindBinary(configuredPath: $this->fakeBinary);
@@ -140,15 +150,10 @@ public function testAutoModeWithAvailableBinaryLogsBinaryIndexer(): void
 
         $this->assertCount(1, $logger->records);
         $this->assertSame('notice', $logger->records[0]['level']);
-        $this->assertStringContainsString('Using binary indexer', $logger->records[0]['message']);
-        $this->assertStringContainsString('auto-detected', $logger->records[0]['message']);
+        $this->assertStringContainsString('Using PHP indexer', $logger->records[0]['message']);
     }
 
-    // -------------------------------------------------------------------
-    // 'auto' mode — binary not available → fallback
-    // -------------------------------------------------------------------
-
-    public function testAutoModeWithoutBinaryFallsBackToPhp(): void
+    public function testAutoModeWithoutBinaryReturnsPhp(): void
     {
         $logger = new IndexerResolverLogger();
         $resolver = new IndexerResolver(new UnavailablePagefindBinary(), $logger);
@@ -158,18 +163,6 @@ public function testAutoModeWithoutBinaryFallsBackToPhp(): void
         $this->assertSame('php', $result);
     }
 
-    public function testAutoModeWithoutBinaryLogsPhpIndexer(): void
-    {
-        $logger = new IndexerResolverLogger();
-        $resolver = new IndexerResolver(new UnavailablePagefindBinary(), $logger);
-
-        $resolver->resolve('auto');
-
-        $this->assertCount(1, $logger->records);
-        $this->assertSame('notice', $logger->records[0]['level']);
-        $this->assertStringContainsString('Using PHP indexer', $logger->records[0]['message']);
-    }
-
     // -------------------------------------------------------------------
     // IndexBuildOrchestrator emits "Using PHP indexer" notice
     // -------------------------------------------------------------------