fix: avoid int64->int truncation in NumericFilter.EqValue on 32-bit arch

EqValue() previously returned int, silently truncating int64 values that
exceed math.MaxInt32 on 32-bit architectures. Change the return type to
int64 and update callers (ior.go, filterstack.go) with explicit int()
casts that are safe because Linux PID/TID values never exceed 4194304.
Add TestEqValueReturnsInt64PreservesLargeValues to guard the fix.

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

1 files changed, 4 insertions, 2 deletions

diff --git a/internal/tui/filterstack.go b/internal/tui/filterstack.go
index 28667d9..b60f322 100644
--- a/internal/tui/filterstack.go
+++ b/internal/tui/filterstack.go
@@ -87,15 +87,17 @@ func (f *filterStack) rebindProcessFilters(pid, tid int) {
 // pidFromFilter extracts the PID equality value from the active filter.
 // Returns -1 (meaning "no filter") when no equality constraint is set.
 func (f *filterStack) pidFromFilter() int {
+	// EqValue returns int64; PID values are always within int range (Linux PID_MAX ≤ 4194304).
 	pid, _ := f.global.PID.EqValue()
-	return selectedPIDFilter(pid)
+	return selectedPIDFilter(int(pid))
 }
 
 // tidFromFilter extracts the TID equality value from the active filter.
 // Returns -1 (meaning "no filter") when no equality constraint is set.
 func (f *filterStack) tidFromFilter() int {
+	// EqValue returns int64; TID values are always within int range (Linux PID_MAX ≤ 4194304).
 	tid, _ := f.global.TID.EqValue()
-	return selectedPIDFilter(tid)
+	return selectedPIDFilter(int(tid))
 }
 
 // labelStack returns the current human-readable filter label stack (read-only).