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>

1 files changed, 6 insertions, 3 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
 	}