llm: add compile-time interface checks for all providers

Add the missing var _ Client / var _ Streamer compile-time satisfaction
check to anthropicClient, and clarify the existing assertion comments for
openAIClient, openRouterClient, ollamaClient (all Client+Streamer) and
youSearchClient (Client only; the You.com research API is non-streaming).
All providers use value receivers, so assertions use zero-value structs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

5 files changed, 17 insertions, 3 deletions

diff --git a/internal/llm/anthropic.go b/internal/llm/anthropic.go
index 00af17a..6ed808f 100644
--- a/internal/llm/anthropic.go
+++ b/internal/llm/anthropic.go
@@ -25,6 +25,13 @@ type anthropicClient struct {
 	defaultTemperature *float64
 }
 
+// Ensure anthropicClient implements Client and Streamer. All of its methods use
+// value receivers, so the assertions use a zero-value struct (not a pointer).
+var (
+	_ Client   = anthropicClient{}
+	_ Streamer = anthropicClient{}
+)
+
 type anthropicChatRequest struct {
 	Model       string             `json:"model"`
 	Messages    []anthropicMessage `json:"messages"`
diff --git a/internal/llm/ollama.go b/internal/llm/ollama.go
index 83823bc..92fece8 100644
--- a/internal/llm/ollama.go
+++ b/internal/llm/ollama.go
@@ -28,7 +28,8 @@ type ollamaClient struct {
 	defaultTemperature *float64
 }
 
-// Ensure ollamaClient implements Client and Streamer.
+// Ensure ollamaClient implements Client and Streamer. All of its methods use
+// value receivers, so the assertions use a zero-value struct (not a pointer).
 var (
 	_ Client   = ollamaClient{}
 	_ Streamer = ollamaClient{}
diff --git a/internal/llm/openai.go b/internal/llm/openai.go
index 983723a..25696ce 100644
--- a/internal/llm/openai.go
+++ b/internal/llm/openai.go
@@ -25,7 +25,8 @@ type openAIClient struct {
 	defaultTemperature *float64
 }
 
-// Ensure openAIClient implements Client and Streamer.
+// Ensure openAIClient implements Client and Streamer. All of its methods use
+// value receivers, so the assertions use a zero-value struct (not a pointer).
 var (
 	_ Client   = openAIClient{}
 	_ Streamer = openAIClient{}
diff --git a/internal/llm/openrouter.go b/internal/llm/openrouter.go
index 970ec29..567a2c0 100644
--- a/internal/llm/openrouter.go
+++ b/internal/llm/openrouter.go
@@ -22,7 +22,8 @@ type openRouterClient struct {
 	defaultTemperature *float64
 }
 
-// Ensure openRouterClient implements Client and Streamer.
+// Ensure openRouterClient implements Client and Streamer. All of its methods
+// use value receivers, so the assertions use a zero-value struct (not a pointer).
 var (
 	_ Client   = openRouterClient{}
 	_ Streamer = openRouterClient{}
diff --git a/internal/llm/yousearch.go b/internal/llm/yousearch.go
index 66cfb35..8990c26 100644
--- a/internal/llm/yousearch.go
+++ b/internal/llm/yousearch.go
@@ -26,6 +26,10 @@ type youSearchClient struct {
 	chatLogger     logging.ChatLogger
 }
 
+// Ensure youSearchClient implements Client. It does not implement Streamer
+// because the You.com research API returns a single completed result rather
+// than a token stream. Methods use value receivers, so the assertion uses a
+// zero-value struct (not a pointer).
 var _ Client = youSearchClient{}
 
 type youSearchRequest struct {