Thread context.Context through blocking I/O entry points

Accept ctx as the first parameter on the blocking I/O entry points and
propagate it to downstream blocking calls so the work is cancellable from
the process entry point:

- appconfig.Load / LoadWithOptions: honor ctx before the blocking file
  reads, returning defaults on a cancelled context.
- LSP: lsp.Server.Run(ctx) ties the serve loop to the caller context via a
  new watchParentContext bridge (cancels the server context, aborting
  in-flight LLM work). Threaded through hexailsp.Run/RunWithConfig/
  RunWithFactory and runtimeconfig.Store.Reload.
- MCP: mcp.Server.Run(ctx) stops accepting requests once ctx is cancelled;
  threaded through hexaimcp.Run/RunWithFactory/RunBackfill.
- editor: RunEditor/OpenTempAndEdit/OpenFile take ctx and use
  exec.CommandContext so a cancelled context kills the editor subprocess;
  threaded through hexaicli, hexaiaction and askcli call sites.

Top-level callers (cmd/hexai-lsp-server, cmd/hexai-mcp-server) now build a
signal-cancelled context (SIGINT/SIGTERM) so shutdown tears the run down
cleanly. Updated comments to explain the cancellation flow and added
cancellation tests for the LSP/MCP loops, editor, and config load.

All tests pass with -race; cross-package coverage 86.2%.

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

2 files changed, 12 insertions, 8 deletions

diff --git a/internal/runtimeconfig/store.go b/internal/runtimeconfig/store.go
index b8d34b4..4e119b9 100644
--- a/internal/runtimeconfig/store.go
+++ b/internal/runtimeconfig/store.go
@@ -1,6 +1,7 @@
 package runtimeconfig
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"reflect"
@@ -79,9 +80,11 @@ func (s *Store) Set(cfg appconfig.App) []Change {
 	return changes
 }
 
-// Reload re-reads configuration using the supplied options and applies it when valid.
-func (s *Store) Reload(logger *log.Logger, opts appconfig.LoadOptions) ([]Change, error) {
-	cfg := appconfig.LoadWithOptions(logger, opts)
+// Reload re-reads configuration using the supplied options and applies it when
+// valid. ctx is forwarded to the config loader so a cancelled caller (e.g. a
+// shutting-down server) aborts the blocking file reads.
+func (s *Store) Reload(ctx context.Context, logger *log.Logger, opts appconfig.LoadOptions) ([]Change, error) {
+	cfg := appconfig.LoadWithOptions(ctx, logger, opts)
 	if err := cfg.Validate(); err != nil {
 		return nil, err
 	}
diff --git a/internal/runtimeconfig/store_test.go b/internal/runtimeconfig/store_test.go
index ca201a2..a1cce15 100644
--- a/internal/runtimeconfig/store_test.go
+++ b/internal/runtimeconfig/store_test.go
@@ -2,6 +2,7 @@ package runtimeconfig
 
 import (
 	"bytes"
+	"context"
 	"io"
 	"log"
 	"os"
@@ -28,7 +29,7 @@ func TestStoreReloadSkipsEnvOverrides(t *testing.T) {
 	t.Setenv("HEXAI_MAX_TOKENS", "321")
 	t.Setenv("HEXAI_PROVIDER", "")
 
-	initial := appconfig.Load(logger)
+	initial := appconfig.Load(context.Background(), logger)
 	if initial.MaxTokens != 321 {
 		t.Fatalf("expected env override to win initial load, got %d", initial.MaxTokens)
 	}
@@ -38,7 +39,7 @@ func TestStoreReloadSkipsEnvOverrides(t *testing.T) {
 		t.Fatalf("failed to update config file: %v", err)
 	}
 
-	changes, err := store.Reload(logger, appconfig.LoadOptions{IgnoreEnv: true})
+	changes, err := store.Reload(context.Background(), logger, appconfig.LoadOptions{IgnoreEnv: true})
 	if err != nil {
 		t.Fatalf("reload failed: %v", err)
 	}
@@ -78,13 +79,13 @@ func TestStoreReloadLogsSummary(t *testing.T) {
 	t.Setenv("HEXAI_MAX_TOKENS", "321")
 	t.Setenv("HEXAI_PROVIDER", "")
 
-	initial := appconfig.Load(logger)
+	initial := appconfig.Load(context.Background(), logger)
 	store := New(initial)
 	if err := os.WriteFile(configPath, []byte("[general]\nmax_tokens = 128\n"), 0o644); err != nil {
 		t.Fatalf("update config: %v", err)
 	}
 
-	_, err := store.Reload(logger, appconfig.LoadOptions{IgnoreEnv: true})
+	_, err := store.Reload(context.Background(), logger, appconfig.LoadOptions{IgnoreEnv: true})
 	if err != nil {
 		t.Fatalf("reload failed: %v", err)
 	}
@@ -182,7 +183,7 @@ func TestReload_NilLogger(t *testing.T) {
 	// in Reload (skipping logger.Print). LoadWithOptions returns defaults when
 	// logger is nil, so the store gets default config applied.
 	store := New(appconfig.App{CoreConfig: appconfig.CoreConfig{MaxTokens: 1}})
-	changes, err := store.Reload(nil, appconfig.LoadOptions{IgnoreEnv: true})
+	changes, err := store.Reload(context.Background(), nil, appconfig.LoadOptions{IgnoreEnv: true})
 	if err != nil {
 		t.Fatalf("reload failed: %v", err)
 	}