Add memory tool call metrics to memories extension (#24583)

## Why

The memories extension now receives a metrics exporter, but the useful
extension-owned signal is the memory tool call itself: which operation
ran, which memory area it touched, whether the backend call succeeded,
and whether the result was truncated.

## What changed

- Added the `codex.memories.tool.call` counter in
`ext/memories/src/metrics.rs`.
- Emit that counter from `memories/add_ad_hoc_note`, `memories/list`,
`memories/read`, and `memories/search` after backend execution.
- Tag each call with `tool`, `operation`, `scope`, `status`, and
`truncated`.
- Pass the existing `MetricsClient` through the memories extension into
the tool executors; tests use `None`.

## Verification

- `just test -p codex-memories-extension`

codex-rs/ext/memories/src/tools/ad_hoc_note.rs

@@ -3,6 +3,7 @@ use codex_extension_api::ToolCall;
 use codex_extension_api::ToolExecutor;
 use codex_extension_api::ToolName;
 use codex_extension_api::ToolSpec;
+use codex_otel::MetricsClient;
 use schemars::JsonSchema;
 use serde::Deserialize;
 use serde_json::json;
@@ -11,6 +12,7 @@ use crate::ADD_AD_HOC_NOTE_TOOL_NAME;
 use crate::backend::AddAdHocMemoryNoteRequest;
 use crate::backend::AddAdHocMemoryNoteResponse;
 use crate::backend::MemoriesBackend;
+use crate::metrics::record_tool_call;
 
 use super::backend_error_to_function_call;
 use super::memory_function_tool;
@@ -36,6 +38,7 @@ struct AddAdHocNoteArgs {
 #[derive(Clone)]
 pub(super) struct AddAdHocNoteTool<B> {
     pub(super) backend: B,
+    pub(super) metrics_client: Option<MetricsClient>,
 }
 
 #[async_trait::async_trait]
@@ -66,8 +69,15 @@ where
                 filename: args.filename,
                 note: args.note,
             })
-            .await
-            .map_err(backend_error_to_function_call)?;
+            .await;
+        record_tool_call(
+            self.metrics_client.as_ref(),
+            ADD_AD_HOC_NOTE_TOOL_NAME,
+            "ad_hoc_notes",
+            response.is_ok(),
+            "not_applicable",
+        );
+        let response = response.map_err(backend_error_to_function_call)?;
         Ok(Box::new(JsonToolOutput::new(json!(response))))
     }
 }

codex-rs/ext/memories/src/tools/list.rs

@@ -3,6 +3,7 @@ use codex_extension_api::ToolCall;
 use codex_extension_api::ToolExecutor;
 use codex_extension_api::ToolName;
 use codex_extension_api::ToolSpec;
+use codex_otel::MetricsClient;
 use schemars::JsonSchema;
 use serde::Deserialize;
 use serde_json::json;
@@ -13,6 +14,9 @@ use crate::MAX_LIST_RESULTS;
 use crate::backend::ListMemoriesRequest;
 use crate::backend::ListMemoriesResponse;
 use crate::backend::MemoriesBackend;
+use crate::metrics::record_tool_call;
+use crate::metrics::scope_from_optional_path;
+use crate::metrics::truncated_tag;
 
 use super::backend_error_to_function_call;
 use super::clamp_max_results;
@@ -32,6 +36,7 @@ struct ListArgs {
 #[derive(Clone)]
 pub(super) struct ListTool<B> {
     pub(super) backend: B,
+    pub(super) metrics_client: Option<MetricsClient>,
 }
 
 #[async_trait::async_trait]
@@ -57,6 +62,7 @@ where
     {
         let backend = self.backend.clone();
         let args: ListArgs = parse_args(&call)?;
+        let scope = scope_from_optional_path(args.path.as_deref(), "root");
         let response = backend
             .list(ListMemoriesRequest {
                 path: args.path,
@@ -67,8 +73,15 @@ where
                     MAX_LIST_RESULTS,
                 ),
             })
-            .await
-            .map_err(backend_error_to_function_call)?;
+            .await;
+        record_tool_call(
+            self.metrics_client.as_ref(),
+            LIST_TOOL_NAME,
+            scope,
+            response.is_ok(),
+            truncated_tag(response.as_ref().ok().map(|response| response.truncated)),
+        );
+        let response = response.map_err(backend_error_to_function_call)?;
         Ok(Box::new(JsonToolOutput::new(json!(response))))
     }
 }

codex-rs/ext/memories/src/tools/mod.rs

@@ -7,6 +7,7 @@ use codex_extension_api::ToolExecutor;
 use codex_extension_api::ToolName;
 use codex_extension_api::ToolSpec;
 use codex_extension_api::parse_tool_input_schema;
+use codex_otel::MetricsClient;
 use codex_tools::ResponsesApiNamespace;
 use codex_tools::ResponsesApiNamespaceTool;
 use codex_tools::default_namespace_description;
@@ -24,21 +25,30 @@ mod list;
 mod read;
 mod search;
 
-pub(crate) fn memory_tools<B>(backend: B) -> Vec<Arc<dyn ToolExecutor<ToolCall>>>
+pub(crate) fn memory_tools<B>(
+    backend: B,
+    metrics_client: Option<MetricsClient>,
+) -> Vec<Arc<dyn ToolExecutor<ToolCall>>>
 where
     B: MemoriesBackend,
 {
     vec![
         Arc::new(ad_hoc_note::AddAdHocNoteTool {
             backend: backend.clone(),
+            metrics_client: metrics_client.clone(),
         }),
         Arc::new(list::ListTool {
             backend: backend.clone(),
+            metrics_client: metrics_client.clone(),
         }),
         Arc::new(read::ReadTool {
             backend: backend.clone(),
+            metrics_client: metrics_client.clone(),
+        }),
+        Arc::new(search::SearchTool {
+            backend,
+            metrics_client,
         }),
-        Arc::new(search::SearchTool { backend }),
     ]
 }
 

codex-rs/ext/memories/src/tools/read.rs

@@ -3,6 +3,7 @@ use codex_extension_api::ToolCall;
 use codex_extension_api::ToolExecutor;
 use codex_extension_api::ToolName;
 use codex_extension_api::ToolSpec;
+use codex_otel::MetricsClient;
 use schemars::JsonSchema;
 use serde::Deserialize;
 use serde_json::json;
@@ -12,6 +13,9 @@ use crate::READ_TOOL_NAME;
 use crate::backend::MemoriesBackend;
 use crate::backend::ReadMemoryRequest;
 use crate::backend::ReadMemoryResponse;
+use crate::metrics::record_tool_call;
+use crate::metrics::scope_from_path;
+use crate::metrics::truncated_tag;
 
 use super::backend_error_to_function_call;
 use super::memory_function_tool;
@@ -31,6 +35,7 @@ struct ReadArgs {
 #[derive(Clone)]
 pub(super) struct ReadTool<B> {
     pub(super) backend: B,
+    pub(super) metrics_client: Option<MetricsClient>,
 }
 
 #[async_trait::async_trait]
@@ -56,15 +61,24 @@ where
     {
         let backend = self.backend.clone();
         let args: ReadArgs = parse_args(&call)?;
+        let path = args.path;
+        let scope = scope_from_path(path.as_str());
         let response = backend
             .read(ReadMemoryRequest {
-                path: args.path,
+                path: path.clone(),
                 line_offset: args.line_offset.unwrap_or(1),
                 max_lines: args.max_lines,
                 max_tokens: DEFAULT_READ_MAX_TOKENS,
             })
-            .await
-            .map_err(backend_error_to_function_call)?;
+            .await;
+        record_tool_call(
+            self.metrics_client.as_ref(),
+            READ_TOOL_NAME,
+            scope,
+            response.is_ok(),
+            truncated_tag(response.as_ref().ok().map(|response| response.truncated)),
+        );
+        let response = response.map_err(backend_error_to_function_call)?;
         Ok(Box::new(JsonToolOutput::new(json!(response))))
     }
 }

codex-rs/ext/memories/src/tools/search.rs

@@ -3,6 +3,7 @@ use codex_extension_api::ToolCall;
 use codex_extension_api::ToolExecutor;
 use codex_extension_api::ToolName;
 use codex_extension_api::ToolSpec;
+use codex_otel::MetricsClient;
 use schemars::JsonSchema;
 use serde::Deserialize;
 use serde_json::json;
@@ -14,6 +15,9 @@ use crate::backend::MemoriesBackend;
 use crate::backend::SearchMatchMode;
 use crate::backend::SearchMemoriesRequest;
 use crate::backend::SearchMemoriesResponse;
+use crate::metrics::record_tool_call;
+use crate::metrics::scope_from_optional_path;
+use crate::metrics::truncated_tag;
 
 use super::backend_error_to_function_call;
 use super::clamp_max_results;
@@ -40,6 +44,7 @@ struct SearchArgs {
 #[derive(Clone)]
 pub(super) struct SearchTool<B> {
     pub(super) backend: B,
+    pub(super) metrics_client: Option<MetricsClient>,
 }
 
 #[async_trait::async_trait]
@@ -65,10 +70,16 @@ where
     {
         let backend = self.backend.clone();
         let args: SearchArgs = parse_args(&call)?;
-        let response = backend
-            .search(args.into_request())
-            .await
-            .map_err(backend_error_to_function_call)?;
+        let scope = scope_from_optional_path(args.path.as_deref(), "all");
+        let response = backend.search(args.into_request()).await;
+        record_tool_call(
+            self.metrics_client.as_ref(),
+            SEARCH_TOOL_NAME,
+            scope,
+            response.is_ok(),
+            truncated_tag(response.as_ref().ok().map(|response| response.truncated)),
+        );
+        let response = response.map_err(backend_error_to_function_call)?;
         Ok(Box::new(JsonToolOutput::new(json!(response))))
     }
 }