Declare only the tables and columns pixa writes and reads (closes #310)

Removes output_content and request_cache, which nothing writes, and every
column that was written but never read: the host, path, query and
fetched_at of source_content, the content_type and created_at of
variant_content, and the status_code, error_message and fetched_at of
negative_cache.

StoreVariant no longer takes a content type and StoreNegative no longer
takes a status code or message, so extractStatusCode and the status
constants, which only fed status_code, are gone. Reconciliation adopts a
variant file without opening it, as its row no longer records a content
type. Tests that set or checked a removed column follow.

Model: opus-5-5

README.md

@@ -188,10 +188,10 @@ allowlisted source hosts for open access.
 name.
 
 Each source image and each transformed image has one row in the database,
-holding its size and when it was last used. Two source URLs that serve the same
+holding its size and when it was last used; a source image's row also holds its
-bytes are stored twice, once under each URL. A source image is stored by writing
+content type. Two source URLs that serve the same bytes are stored twice, once
-its file and then its row; when the row cannot be written, the file is removed
+under each URL. A source image is stored by writing its file and then its row;
-again.
+when the row cannot be written, the file is removed again.
 
 Source and transformed image files are written under a temporary name, synced to
 disk, and only then renamed into place, so a crash leaves no file under its own

TODO.md

@@ -32,13 +32,12 @@ P2: security: per-origin rate limiting
 
 - 2026-10-21 the schema file declares only the tables and columns pixa writes
   and reads (closes #310): `output_content` and `request_cache` are gone, and so
-  are the columns nothing read: the host, path, query, `content_type` and
+  are the columns nothing read: the host, path, query and `fetched_at` of
-  `fetched_at` of `source_content`, the `content_type` and `created_at` of
+  `source_content`, the `content_type` and `created_at` of `variant_content`,
-  `variant_content`, and the `status_code`, `error_message` and `fetched_at` of
+  and the `status_code`, `error_message` and `fetched_at` of `negative_cache`.
-  `negative_cache`. `StoreSource` no longer takes the fetch result,
+  `StoreVariant` no longer takes a content type, `StoreNegative` no longer takes
-  `LookupSource` returns only the source key, `StoreVariant` no longer takes a
+  a status code or message, and reconciliation adopts a variant file without
-  content type, `StoreNegative` no longer takes a status code or message, and
+  reading its first bytes.
-  reconciliation adopts a variant file without reading its first bytes.
 - 2026-10-21 a cache hit makes no database call (closes #309): `Service.Get`
   opens the variant file with `Cache.GetVariant` and nothing else, with no
   existence check first. The content type comes from the file's first bytes; a

internal/database/concurrent_writes_internal_test.go

@@ -131,7 +131,7 @@ func writeLikeOneRequest(ctx context.Context, db *sql.DB, key string) error {
 	}
 
 	_, err = db.ExecContext(ctx, `INSERT INTO source_content
-		(source_key, size_bytes) VALUES (?, 1)`, key)
+		(source_key, content_type, size_bytes) VALUES (?, 'image/png', 1)`, key)
 	if err != nil {
 		return fmt.Errorf("storing a source: %w", err)
 	}

internal/db/migrations/001_schema.sql

@@ -6,6 +6,7 @@
 -- is the SHA-256 of the source's host, path and query
 CREATE TABLE IF NOT EXISTS source_content (
     source_key TEXT PRIMARY KEY,
+    content_type TEXT NOT NULL,
     size_bytes INTEGER NOT NULL,
     last_accessed_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
 );

internal/imgcache/cache.go

@@ -12,6 +12,7 @@ import (
 	"sync/atomic"
 	"time"
 
+	"sneak.berlin/go/pixa/internal/httpfetcher"
 	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
@@ -211,6 +212,7 @@ func (c *Cache) StoreSource(
 	ctx context.Context,
 	req *imagerequest.Request,
 	content io.Reader,
+	result *httpfetcher.FetchResult,
 ) (imagerequest.SourceKey, error) {
 	if c.disabled {
 		return "", nil
@@ -229,12 +231,13 @@ func (c *Cache) StoreSource(
 	}
 
 	_, err = c.db.ExecContext(ctx, `
-		INSERT INTO source_content (source_key, size_bytes)
+		INSERT INTO source_content (source_key, content_type, size_bytes)
-		VALUES (?, ?)
+		VALUES (?, ?, ?)
 		ON CONFLICT(source_key) DO UPDATE SET
+			content_type = excluded.content_type,
 			size_bytes = excluded.size_bytes,
 			last_accessed_at = CURRENT_TIMESTAMP
-	`, string(key), size)
+	`, string(key), result.ContentType, size)
 	if err != nil {
 		deleteErr := c.srcContent.Delete(key)
 		if deleteErr != nil {
@@ -284,41 +287,41 @@ func (c *Cache) StoreVariant(
 }
 
 // LookupSource checks if we have cached source content for a request.
-// Returns the source key if found, or an empty key if not; a row whose
+// Returns the source key and content type if found, or empty values
-// file is missing is not found. A source found has its access time
+// if not; a row whose file is missing is not found. A source found has
-// handed to the background writer without waiting (see
+// its access time handed to the background writer without waiting (see
 // touchSourceContent); a disabled cache always reports no cached source.
 func (c *Cache) LookupSource(
 	ctx context.Context, req *imagerequest.Request,
-) (imagerequest.SourceKey, error) {
+) (imagerequest.SourceKey, string, error) {
 	if c.disabled {
-		return "", nil
+		return "", "", nil
 	}
 
 	key := req.Source.Key()
 
-	var foundKey string
+	var contentType string
 
 	err := c.db.QueryRowContext(ctx, `
-		SELECT source_key FROM source_content WHERE source_key = ?
+		SELECT content_type FROM source_content WHERE source_key = ?
-	`, string(key)).Scan(&foundKey)
+	`, string(key)).Scan(&contentType)
 
 	if errors.Is(err, sql.ErrNoRows) {
-		return "", nil
+		return "", "", nil
 	}
 
 	if err != nil {
-		return "", fmt.Errorf("failed to lookup source: %w", err)
+		return "", "", fmt.Errorf("failed to lookup source: %w", err)
 	}
 
 	// Verify the content file exists
 	if !c.srcContent.Exists(key) {
-		return "", nil
+		return "", "", nil
 	}
 
 	c.touchSourceContent(key)
 
-	return key, nil
+	return key, contentType, nil
 }
 
 // StoreNegative stores a negative cache entry for a failed fetch.

internal/imgcache/cache_internal_test.go

@@ -22,6 +22,7 @@ func setupTestDB(t *testing.T) *sql.DB {
 	schema := `
 		CREATE TABLE source_content (
 			source_key TEXT PRIMARY KEY,
+			content_type TEXT NOT NULL,
 			size_bytes INTEGER NOT NULL,
 			last_accessed_at DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP
 		);

internal/imgcache/eviction_internal_test.go

@@ -16,6 +16,7 @@ import (
 
 	"modernc.org/sqlite"
 	"sneak.berlin/go/pixa/internal/database"
+	"sneak.berlin/go/pixa/internal/httpfetcher"
 	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
@@ -101,8 +102,17 @@ func storeEvictionTestSource(
 		},
 	}
 
+	result := &httpfetcher.FetchResult{
+		StatusCode:    200,
+		ContentType:   testContentTypeJPEG,
+		ContentLength: int64(len(content)),
+		Headers: map[string][]string{
+			testHeaderContentType: {testContentTypeJPEG},
+		},
+	}
+
 	key, err := cache.StoreSource(
-		context.Background(), req, bytes.NewReader(content),
+		context.Background(), req, bytes.NewReader(content), result,
 	)
 	if err != nil {
 		t.Fatalf("StoreSource(%s%s) failed: %v", host, path, err)
@@ -433,7 +443,14 @@ func assertDisabledCacheWritesAreNoOps(
 		t.Fatalf("StoreVariant on disabled cache must be a no-op, got error: %v", err)
 	}
 
-	key, err := cache.StoreSource(ctx, req, bytes.NewReader([]byte("data")))
+	result := &httpfetcher.FetchResult{
+		StatusCode:    200,
+		ContentType:   testContentTypeJPEG,
+		ContentLength: 4,
+		Headers:       map[string][]string{},
+	}
+
+	key, err := cache.StoreSource(ctx, req, bytes.NewReader([]byte("data")), result)
 	if err != nil {
 		t.Fatalf("StoreSource on disabled cache must be a no-op, got error: %v", err)
 	}
@@ -452,13 +469,14 @@ func assertDisabledCacheReadsAlwaysMiss(
 
 	ctx := t.Context()
 
-	key, err := cache.LookupSource(ctx, req)
+	key, srcType, err := cache.LookupSource(ctx, req)
 	if err != nil {
 		t.Fatalf("LookupSource on disabled cache failed: %v", err)
 	}
 
-	if key != "" {
+	if key != "" || srcType != "" {
-		t.Errorf("LookupSource on disabled cache = %q, want empty", key)
+		t.Errorf("LookupSource on disabled cache = (%q, %q), want empty",
+			key, srcType)
 	}
 }
 

internal/imgcache/max_concurrent_processing_internal_test.go

@@ -77,7 +77,7 @@ func TestService_Get_WaitsForSlotBeforeReadingCachedSource(t *testing.T) {
 
 	_ = resp.Content.Close()
 
-	sourceKey, err := svc.cache.LookupSource(t.Context(),
+	sourceKey, _, err := svc.cache.LookupSource(t.Context(),
 		widthOnlyRequest(fixtures, 50))
 	if err != nil || sourceKey == "" {
 		t.Fatalf("LookupSource() = %q, %v; want the cached source",

internal/imgcache/negative_cache_internal_test.go

@@ -146,7 +146,7 @@ func TestService_Get_ServesCachedVariantOfNegativeCachedURL(t *testing.T) {
 
 	_ = resp.Content.Close()
 
-	sourceKey, err := svc.cache.LookupSource(t.Context(),
+	sourceKey, _, err := svc.cache.LookupSource(t.Context(),
 		photoVariant(fixtures, 85, imagerequest.FitCover))
 	if err != nil || sourceKey == "" {
 		t.Fatalf("LookupSource() = %q, %v, want the cached source", sourceKey, err)

internal/imgcache/partial_cache_files_internal_test.go

@@ -65,7 +65,7 @@ func cachedSourcePath(
 ) string {
 	t.Helper()
 
-	sourceKey, err := svc.cache.LookupSource(t.Context(), req)
+	sourceKey, _, err := svc.cache.LookupSource(t.Context(), req)
 	if err != nil || sourceKey == "" {
 		t.Fatalf("LookupSource() = %q, %v; want the cached source", sourceKey, err)
 	}

internal/imgcache/pendingcounts_internal_test.go

@@ -364,7 +364,7 @@ func TestLookupSource_HandsAccessTimeToTheBackgroundWriter(t *testing.T) {
 	`
 	anHourAgoInDatabase := anHourAgo.UTC().Format(sqliteTimestampFormat)
 
-	found, err := cache.LookupSource(t.Context(), &imagerequest.Request{
+	found, _, err := cache.LookupSource(t.Context(), &imagerequest.Request{
 		Source: imagerequest.Source{Host: "example.com", Path: "/photo.jpg"},
 	})
 	if err != nil || found != key {

internal/imgcache/service.go

@@ -397,7 +397,7 @@ func (s *Service) processFromSourceOrFetch(
 	cacheKey imagerequest.VariantKey,
 ) (*processedVariant, error) {
 	// Check if we have cached source content
-	sourceKey, err := s.cache.LookupSource(ctx, req)
+	sourceKey, _, err := s.cache.LookupSource(ctx, req)
 	if err != nil {
 		s.log.Warn("source lookup failed", "error", err)
 	}
@@ -518,7 +518,7 @@ func (s *Service) fetchAndProcess(
 	}
 
 	// Store source content
-	_, err = s.cache.StoreSource(ctx, req, bytes.NewReader(sourceData))
+	_, err = s.cache.StoreSource(ctx, req, bytes.NewReader(sourceData), fetchResult)
 	if err != nil {
 		s.log.Warn("failed to store source content", "error", err)
 		// Continue even if caching fails

internal/imgcache/source_content_internal_test.go

@@ -7,6 +7,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"sneak.berlin/go/pixa/internal/httpfetcher"
 	"sneak.berlin/go/pixa/internal/imagerequest"
 )
 
@@ -84,10 +85,10 @@ func TestEvictSourceBlob_LeavesSourceWithIdenticalBytesServed(t *testing.T) {
 		t.Errorf("the evicted source still has %d source_content rows", n)
 	}
 
-	kept, err := cache.LookupSource(t.Context(), &imagerequest.Request{
+	kept, contentType, err := cache.LookupSource(t.Context(), &imagerequest.Request{
 		Source: imagerequest.Source{Host: testHostCDN, Path: "/kept.jpg"},
 	})
-	t.Logf("LookupSource() of the kept source = %q, error %v", kept, err)
+	t.Logf("LookupSource() of the kept source = %q, %q, error %v", kept, contentType, err)
 
 	if err != nil || kept == "" {
 		t.Fatalf("LookupSource() of the kept source = %q, %v; want it cached", kept, err)
@@ -127,8 +128,10 @@ func TestStoreSource_FailedRowWriteLeavesNoFile(t *testing.T) {
 	req := &imagerequest.Request{
 		Source: imagerequest.Source{Host: testHostCDN, Path: testPathCat},
 	}
+	result := &httpfetcher.FetchResult{ContentType: testContentTypeJPEG}
+
 	key, err := cache.StoreSource(t.Context(), req,
-		bytes.NewReader([]byte("source bytes")))
+		bytes.NewReader([]byte("source bytes")), result)
 	t.Logf("StoreSource() = %q, error = %v", key, err)
 
 	if err == nil {

internal/imgcache/testutil_internal_test.go

@@ -20,10 +20,11 @@ import (
 
 // Shared test data literals, extracted as constants for goconst.
 const (
-	testHostCDN         = "cdn.example.com"
+	testHostCDN           = "cdn.example.com"
-	testHostExample     = "example.com"
+	testHostExample       = "example.com"
-	testPathCat         = "/photos/cat.jpg"
+	testPathCat           = "/photos/cat.jpg"
-	testContentTypeJPEG = "image/jpeg"
+	testContentTypeJPEG   = "image/jpeg"
+	testHeaderContentType = "Content-Type"
 )
 
 // TestFixtures contains paths to test files in the mock filesystem.