Enable FTS5 Porter stemmer for skill search (#49)

* Add lightweight database migration system (#44)

Replace inline schema constant in DatabaseInitializer with numbered SQL
migration files and a SchemaMigrator that tracks applied versions in a
schema_version table. Existing databases are handled safely via
IF NOT EXISTS clauses in migration 001.

* Enable FTS5 Porter stemmer for skill search (#43)

Add migration 002 to rebuild the FTS5 virtual table with
tokenize='porter unicode61' so inflected search terms like
"closed deals" and "closing" match skills containing "close deal".

Author: Aaronontheweb

src/SkillServer/migrations/002_fts5_porter_stemmer.sql

@@ -0,0 +1,43 @@
+-- 002_fts5_porter_stemmer.sql: Enable Porter stemmer for better search matching
+
+-- Drop existing triggers before dropping the table
+DROP TRIGGER IF EXISTS trg_skills_fts_insert;
+DROP TRIGGER IF EXISTS trg_skills_fts_delete;
+
+-- Recreate FTS table with porter stemmer tokenizer
+DROP TABLE IF EXISTS skills_fts;
+
+CREATE VIRTUAL TABLE skills_fts USING fts5(
+    name,
+    description,
+    category,
+    tokenize='porter unicode61'
+);
+
+-- Recreate triggers to keep FTS in sync
+CREATE TRIGGER trg_skills_fts_insert
+AFTER INSERT ON skill_versions
+WHEN NEW.is_latest = 1
+BEGIN
+    DELETE FROM skills_fts WHERE rowid = NEW.skill_id;
+    INSERT INTO skills_fts(rowid, name, description, category)
+    SELECT NEW.skill_id, s.name, NEW.description, COALESCE(NEW.category, '')
+    FROM skills s WHERE s.id = NEW.skill_id;
+END;
+
+CREATE TRIGGER trg_skills_fts_delete
+AFTER DELETE ON skill_versions
+BEGIN
+    DELETE FROM skills_fts WHERE rowid = OLD.skill_id;
+    INSERT INTO skills_fts(rowid, name, description, category)
+    SELECT s.id, s.name, sv.description, COALESCE(sv.category, '')
+    FROM skills s
+    JOIN skill_versions sv ON sv.skill_id = s.id AND sv.is_latest = 1
+    WHERE s.id = OLD.skill_id;
+END;
+
+-- Repopulate FTS index from existing data
+INSERT INTO skills_fts(rowid, name, description, category)
+SELECT s.id, s.name, sv.description, COALESCE(sv.category, '')
+FROM skills s
+JOIN skill_versions sv ON sv.skill_id = s.id AND sv.is_latest = 1;

tests/SkillServer.Integration.Tests/SkillServerIntegrationTests.cs

@@ -571,4 +571,39 @@ public async Task UploadSkill_DifferentVersions_AreAllowed()
         var versions = await _fixture.Client.GetSkillVersionsAsync(skillName, ct);
         Assert.Equal(2, versions.Count);
     }
+
+    [Fact]
+    public async Task SearchSkills_WithPorterStemming_MatchesStemmedTerms()
+    {
+        var ct = TestContext.Current.CancellationToken;
+        var prefix = $"stem-{Guid.NewGuid():N}"[..10];
+        var skillName = $"{prefix}-closer";
+
+        var skillContent = $"""
+            ---
+            name: {skillName}
+            description: Helps sales reps close deal opportunities faster
+            ---
+
+            # Stemming Test
+            """;
+
+        using var content = new MultipartFormDataContent();
+        content.Add(new StringContent(skillName), "name");
+        content.Add(new StringContent("1.0.0"), "version");
+
+        var fileContent = new ByteArrayContent(Encoding.UTF8.GetBytes(skillContent));
+        fileContent.Headers.ContentType = new MediaTypeHeaderValue("text/markdown");
+        content.Add(fileContent, "file", "SKILL.md");
+
+        await _fixture.AuthenticatedHttpClient.PostAsync("/skills", content, ct);
+
+        // "closed deals" should match "close deal" via porter stemming
+        var results = await _fixture.Client.SearchSkillsAsync("closed deals", ct: ct);
+        Assert.Contains(results, s => s.Name == skillName);
+
+        // "closing" should match "close" via stemming
+        results = await _fixture.Client.SearchSkillsAsync("closing", ct: ct);
+        Assert.Contains(results, s => s.Name == skillName);
+    }
 }