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, 5 insertions, 4 deletions

diff --git a/internal/appconfig/config_env_model_test.go b/internal/appconfig/config_env_model_test.go
index e10fa5d..9856a4e 100644
--- a/internal/appconfig/config_env_model_test.go
+++ b/internal/appconfig/config_env_model_test.go
@@ -1,6 +1,7 @@
 package appconfig
 
 import (
+	"context"
 	"log"
 	"os"
 	"testing"
@@ -12,14 +13,14 @@ func TestEnv_GenericModelOverrideAndPrecedence(t *testing.T) {
 	t.Setenv("HEXAI_MODEL", "gpt-5-codex")
 	t.Setenv("HEXAI_PROVIDER", "openai")
 	// No provider-specific env set yet: HEXAI_MODEL should flow into OpenAIModel
-	cfg := Load(log.New(os.Stderr, "test ", 0))
+	cfg := Load(context.Background(), log.New(os.Stderr, "test ", 0))
 	if cfg.OpenAIModel != "gpt-5-codex" {
 		t.Fatalf("expected OpenAIModel=gpt-5-codex via HEXAI_MODEL, got %q", cfg.OpenAIModel)
 	}
 
 	// Now set a provider-specific model; it should win over HEXAI_MODEL
 	t.Setenv("HEXAI_OPENAI_MODEL", "gpt-5-thinking")
-	cfg2 := Load(log.New(os.Stderr, "test ", 0))
+	cfg2 := Load(context.Background(), log.New(os.Stderr, "test ", 0))
 	if cfg2.OpenAIModel != "gpt-5-thinking" {
 		t.Fatalf("expected OpenAIModel from HEXAI_OPENAI_MODEL to win, got %q", cfg2.OpenAIModel)
 	}
@@ -30,7 +31,7 @@ func TestEnv_ModelForce_OverridesProviderSpecific(t *testing.T) {
 	t.Setenv("HEXAI_OPENAI_MODEL", "gpt-5-main")
 	t.Setenv("HEXAI_MODEL_FORCE", "gpt-5-codex")
 	t.Setenv("HEXAI_PROVIDER", "openai")
-	cfg := Load(log.New(os.Stderr, "test ", 0))
+	cfg := Load(context.Background(), log.New(os.Stderr, "test ", 0))
 	if cfg.OpenAIModel != "gpt-5-codex" {
 		t.Fatalf("expected OpenAIModel forced to gpt-5-codex, got %q", cfg.OpenAIModel)
 	}
@@ -43,7 +44,7 @@ func TestEnv_SurfaceModelOverrides(t *testing.T) {
 	t.Setenv("HEXAI_MODEL_CLI", "gpt-cli")
 	t.Setenv("HEXAI_TEMPERATURE_CLI", "0.22")
 	t.Setenv("HEXAI_PROVIDER_CLI", "ollama")
-	cfg := Load(log.New(os.Stderr, "test ", 0))
+	cfg := Load(context.Background(), log.New(os.Stderr, "test ", 0))
 	if len(cfg.CompletionConfigs) != 1 {
 		t.Fatalf("expected single completion entry, got %+v", cfg.CompletionConfigs)
 	}