Runner: the line cap is read once in Start, not per line from a goroutine (issue 1966, review round 3)

Claude-Session: https://claude.ai/code/session_01NcbgfFfQ4Z9UE5jK32PmE5

node-tools/internal/launch/launch.go

@@ -301,6 +301,7 @@ func Start(module, entry string, env []string, mesh Bus, logf func(string, ...an
 	// The restart pauses are read once, here: the exit handling runs on its own goroutine and must not
 	// read the package's settings while a caller (a test) changes them (novox/hq issue 476).
 	pauseFirst, pauseMost, settle := RestartFirst, RestartMost, RestartSettle
+	lineCap := maxLine
 	pause := pauseFirst
 
 	start := func() (*child, error) {
@@ -348,12 +349,12 @@ func Start(module, entry string, env []string, mesh Bus, logf func(string, ...an
 			defer close(c.handled)
 			rd := bufio.NewReaderSize(stdout, 64*1024)
 			for {
-				raw, tooLong, rerr := readCapped(rd, maxLine)
+				raw, tooLong, rerr := readCapped(rd, lineCap)
 				if tooLong {
 					// Never left frozen (issue 1966): a reader that stops while the bundle lives leaves the bundle's
 					// next write blocked for good. Said, and the bundle ended; the exit path below fails what waits
 					// on it and starts it again.
-					reason := fmt.Sprintf("%s's bundle wrote a line over %d bytes (a tool's answer the bus cannot carry)", module, maxLine)
+					reason := fmt.Sprintf("%s's bundle wrote a line over %d bytes (a tool's answer the bus cannot carry)", module, lineCap)
 					logf("[mesh-tools] %s; ending the bundle", reason)
 					c.mu.Lock()
 					c.endedFor = reason