fix: address all HIGH-severity code quality audit findings

- lsp/server.go: track request goroutines in inflight WaitGroup to
  prevent use-after-close writes on shutdown
- lsp/llm_client_registry.go: acquire write lock before calling build()
  to eliminate TOCTOU race on cache population
- lsp/handlers_codeaction.go: resolveSimplifyCodeAction now uses
  PromptCodeActionSimplify{System,User} (was wrongly using rewrite prompts)
- askcli/taskexport.go: remove exported MustParseTaskExport to prevent
  panic on malformed external input; move to unexported test helper
- cmd/ask/main.go: print error to stderr before os.Exit
- llm/{openai,ollama,openrouter}.go: add interface satisfaction assertions
- integrationtests/ask_test.go: replace type assertions with errors.As
  for robust exec.ExitError unwrapping

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

1 files changed, 9 insertions, 8 deletions

diff --git a/integrationtests/ask_test.go b/integrationtests/ask_test.go
index 7dfbcb4..a762b9d 100644
--- a/integrationtests/ask_test.go
+++ b/integrationtests/ask_test.go
@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"os"
 	"os/exec"
@@ -56,8 +57,8 @@ func runAsk(ctx context.Context, args []string) (stdout, stderr bytes.Buffer, ex
 	if err == nil {
 		return
 	}
-	ee, ok := err.(*exec.ExitError)
-	if !ok {
+	var ee *exec.ExitError
+	if !errors.As(err, &ee) {
 		return bytes.Buffer{}, stderr, -1
 	}
 	return stdout, stderr, ee.ExitCode()
@@ -75,8 +76,8 @@ func runAskWithStdin(ctx context.Context, args []string, stdin string) (stdout,
 	if err == nil {
 		return
 	}
-	ee, ok := err.(*exec.ExitError)
-	if !ok {
+	var ee *exec.ExitError
+	if !errors.As(err, &ee) {
 		return bytes.Buffer{}, stderr, -1
 	}
 	return stdout, stderr, ee.ExitCode()
@@ -91,8 +92,8 @@ func runTask(ctx context.Context, args []string) (stdout, stderr bytes.Buffer, e
 	if err == nil {
 		return
 	}
-	ee, ok := err.(*exec.ExitError)
-	if !ok {
+	var ee *exec.ExitError
+	if !errors.As(err, &ee) {
 		return bytes.Buffer{}, stderr, -1
 	}
 	return stdout, stderr, ee.ExitCode()
@@ -108,8 +109,8 @@ func runTaskWithStdin(ctx context.Context, args []string, stdin string) (stdout,
 	if err == nil {
 		return
 	}
-	ee, ok := err.(*exec.ExitError)
-	if !ok {
+	var ee *exec.ExitError
+	if !errors.As(err, &ee) {
 		return bytes.Buffer{}, stderr, -1
 	}
 	return stdout, stderr, ee.ExitCode()