From 7f358602e40e50b00b111f683515f20194e62f31 Mon Sep 17 00:00:00 2001
From: clawbot <35+clawbot@noreply.example.org>
Date: Tue, 29 Sep 2026 07:29:52 +0000
Subject: [PATCH] Keep the content type a store put in memory over one read
 from disk (closes #70)

GetVariant now adds the content type it read from a .meta file only
when memory holds none for the variant, so a type StoreVariant added
meanwhile is not replaced. A read that found no .meta file yet still
gets application/octet-stream for that one request, as before this
change, but no longer leaves it in memory for later hits.

Model: opus-5-5
---
 TODO.md                    | 3 ++-
 internal/imgcache/cache.go | 7 +++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/TODO.md b/TODO.md
index c694ba8..8c80174 100644
--- a/TODO.md
+++ b/TODO.md
@@ -33,7 +33,8 @@ exhaustion
 - 2026-09-29 variant content types kept in memory (closes #70):
   `Cache.metaCache` holds the content types of up to 10,000 variants in an LRU
   (`github.com/hashicorp/golang-lru/v2`), filled by `StoreVariant` and by
-  `GetVariant` after it reads a `.meta` file; for a variant it holds, `Lookup`
+  `GetVariant` after it reads a `.meta` file, where a type `StoreVariant` added
+  meanwhile is kept over the one read; for a variant it holds, `Lookup`
   skips the check of the disk and `GetVariant` skips the `.meta` read, still
   opening the variant file and taking the size from it; eviction removes the
   entry before deleting the files, and `GetVariant` removes it when the file
diff --git a/internal/imgcache/cache.go b/internal/imgcache/cache.go
index 02a8edd..2390988 100644
--- a/internal/imgcache/cache.go
+++ b/internal/imgcache/cache.go
@@ -522,7 +522,10 @@ func (c *Cache) IncrementTransformCount(ctx context.Context) {
 
 // loadVariantWithMeta is GetVariant for a variant metaCache does not
 // hold: it reads the content type from the variant's .meta file and
-// keeps it in metaCache.
+// keeps it in metaCache, unless a StoreVariant has put one there
+// meanwhile. The stored one wins, since this read may have found the
+// variant file before the store wrote the .meta file, and so got
+// application/octet-stream.
 func (c *Cache) loadVariantWithMeta(
 	cacheKey VariantKey,
 ) (io.ReadCloser, int64, string, error) {
@@ -531,7 +534,7 @@ func (c *Cache) loadVariantWithMeta(
 		return nil, 0, "", err
 	}
 
-	c.metaCache.Add(cacheKey, contentType)
+	c.metaCache.ContainsOrAdd(cacheKey, contentType)
 
 	return reader, size, contentType, nil
 }