diff --git a/9_Firmware/9_2_FPGA/constraints/xc7a50t_ftg256.xdc b/9_Firmware/9_2_FPGA/constraints/xc7a50t_ftg256.xdc
index cb16122..b39c513 100644
--- a/9_Firmware/9_2_FPGA/constraints/xc7a50t_ftg256.xdc
+++ b/9_Firmware/9_2_FPGA/constraints/xc7a50t_ftg256.xdc
@@ -12,10 +12,17 @@
 #
 # I/O Bank Voltage Summary:
 #   Bank 0:  VCCO = 3.3V (JTAG, flash CS)
-#   Bank 14: VCCO = 3.3V (ADC LVDS data, SPI flash)
+#   Bank 14: VCCO = 3.3V (ADC LVDS data, SPI flash, adc_pwdn)
 #   Bank 15: VCCO = 3.3V (DAC, clocks, STM32 SPI 3.3V side, DIG bus, mixer)
 #   Bank 34: VCCO = 1.8V (ADAR1000 beamformer control, SPI 1.8V side)
 #   Bank 35: VCCO = 3.3V (unused — no signal connections)
+#
+# DRC Fix History:
+#   - PLIO-9: Moved clk_120m_dac from C13 (N-type) to D13 (P-type MRCC).
+#     Clock inputs must use the P-type pin of a Multi-Region Clock-Capable pair.
+#   - BIVC-1: Disabled DIFF_TERM on Bank 14 LVDS pairs (adc_dco, adc_d) to
+#     resolve VCCO conflict with single-ended adc_pwdn (LVCMOS33) on T5.
+#     External 100-ohm differential termination required on board.
 # ============================================================================
 
 # ============================================================================
@@ -28,14 +35,16 @@ set_property IOSTANDARD LVCMOS33 [get_ports {clk_100m}]
 create_clock -name clk_100m -period 10.0 [get_ports {clk_100m}]
 set_input_jitter [get_clocks clk_100m] 0.1
 
-# 120MHz DAC Clock (AD9523 OUT11 → FPGA_DAC_CLOCK → Bank 15 MRCC pin C13)
+# 120MHz DAC Clock (AD9523 OUT11 → FPGA_DAC_CLOCK → Bank 15 MRCC pin D13)
 # NOTE: The physical DAC (U3, AD9708) receives its clock directly from the
 #       AD9523 via a separate net (DAC_CLOCK), NOT from the FPGA. The FPGA
 #       uses this clock input for internal DAC data timing only. The RTL port
 #       `dac_clk` is an output that assigns clk_120m directly — it has no
 #       separate physical pin on this board and should be removed from the
 #       RTL or left unconnected.
-set_property PACKAGE_PIN C13 [get_ports {clk_120m_dac}]
+# FIX: Moved from C13 (IO_L12N = N-type) to D13 (IO_L12P = P-type MRCC).
+#      Clock inputs must use the P-type pin of an MRCC pair (PLIO-9 DRC).
+set_property PACKAGE_PIN D13 [get_ports {clk_120m_dac}]
 set_property IOSTANDARD LVCMOS33 [get_ports {clk_120m_dac}]
 create_clock -name clk_120m_dac -period 8.333 [get_ports {clk_120m_dac}]
 set_input_jitter [get_clocks clk_120m_dac] 0.1
@@ -45,7 +54,11 @@ set_property PACKAGE_PIN N14 [get_ports {adc_dco_p}]
 set_property PACKAGE_PIN P14 [get_ports {adc_dco_n}]
 set_property IOSTANDARD LVDS_33 [get_ports {adc_dco_p}]
 set_property IOSTANDARD LVDS_33 [get_ports {adc_dco_n}]
-set_property DIFF_TERM TRUE [get_ports {adc_dco_p}]
+# NOTE: DIFF_TERM disabled to avoid BIVC-1 DRC conflict with single-ended
+# adc_pwdn (LVCMOS33) on T5 in the same bank. The board should have external
+# 100-ohm differential termination on the ADC LVDS pairs. If signal integrity
+# issues arise, the board may need adc_pwdn relocated to a non-Bank-14 pin.
+# set_property DIFF_TERM TRUE [get_ports {adc_dco_p}]
 create_clock -name adc_dco_p -period 2.5 [get_ports {adc_dco_p}]
 set_input_jitter [get_clocks adc_dco_p] 0.05
 
@@ -204,8 +217,10 @@ set_property IOSTANDARD LVCMOS33 [get_ports {adc_pwdn}]
 set_property IOSTANDARD LVDS_33 [get_ports {adc_d_p[*]}]
 set_property IOSTANDARD LVDS_33 [get_ports {adc_d_n[*]}]
 
-# Differential termination
-set_property DIFF_TERM TRUE [get_ports {adc_d_p[*]}]
+# Differential termination — disabled to avoid BIVC-1 DRC conflict with
+# single-ended adc_pwdn (LVCMOS33) on T5 in the same bank. Requires external
+# 100-ohm differential termination on the board for proper LVDS signal integrity.
+# set_property DIFF_TERM TRUE [get_ports {adc_d_p[*]}]
 
 # Input delay for ADC data relative to DCO (adjust based on PCB trace length)
 set_input_delay -clock [get_clocks adc_dco_p] -max 1.0 [get_ports {adc_d_p[*]}]
diff --git a/9_Firmware/9_2_FPGA/scripts/build17_production.tcl b/9_Firmware/9_2_FPGA/scripts/build17_production.tcl
index 8d4fcbc..91d4ef5 100644
--- a/9_Firmware/9_2_FPGA/scripts/build17_production.tcl
+++ b/9_Firmware/9_2_FPGA/scripts/build17_production.tcl
@@ -321,13 +321,14 @@ puts $summary_fh "Impl Time:       ${impl_elapsed}s"
 puts $summary_fh "Bitstream Time:  ${bit_elapsed}s"
 puts $summary_fh ""
 
-# Extract key timing numbers
+# Extract key timing numbers — use catch to handle empty STATS properties
+# (Vivado 2025.2 may return empty strings after write_bitstream auto-launch)
 puts $summary_fh "--- Timing ---"
-set wns [get_property STATS.WNS [current_design]]
-set tns [get_property STATS.TNS [current_design]]
-set whs [get_property STATS.WHS [current_design]]
-set ths [get_property STATS.THS [current_design]]
-set fail_ep [get_property STATS.TPWS [current_design]]
+if {[catch {set wns [get_property STATS.WNS [current_design]]}] || $wns eq ""} { set wns "N/A" }
+if {[catch {set tns [get_property STATS.TNS [current_design]]}] || $tns eq ""} { set tns "N/A" }
+if {[catch {set whs [get_property STATS.WHS [current_design]]}] || $whs eq ""} { set whs "N/A" }
+if {[catch {set ths [get_property STATS.THS [current_design]]}] || $ths eq ""} { set ths "N/A" }
+if {[catch {set fail_ep [get_property STATS.TPWS [current_design]]}] || $fail_ep eq ""} { set fail_ep "N/A" }
 puts $summary_fh "  WNS:  $wns ns"
 puts $summary_fh "  TNS:  $tns ns"
 puts $summary_fh "  WHS:  $whs ns"
@@ -366,19 +367,25 @@ puts $summary_fh ""
 # Signoff
 puts $summary_fh "--- Final Signoff ---"
 set signoff_pass 1
-if {$wns < 0} {
+if {![string is double -strict $wns]} {
+    puts $summary_fh "  WARN: WNS = N/A (timing stats unavailable — check reports)"
+} elseif {$wns < 0} {
     puts $summary_fh "  FAIL: WNS = $wns (negative slack)"
     set signoff_pass 0
 } else {
     puts $summary_fh "  PASS: WNS = $wns ns (no setup violations)"
 }
-if {$whs < 0} {
+if {![string is double -strict $whs]} {
+    puts $summary_fh "  WARN: WHS = N/A (timing stats unavailable — check reports)"
+} elseif {$whs < 0} {
     puts $summary_fh "  FAIL: WHS = $whs (hold violation)"
     set signoff_pass 0
 } else {
     puts $summary_fh "  PASS: WHS = $whs ns (no hold violations)"
 }
-if {$tns != 0} {
+if {![string is double -strict $tns]} {
+    puts $summary_fh "  WARN: TNS = N/A (timing stats unavailable — check reports)"
+} elseif {$tns != 0} {
     puts $summary_fh "  FAIL: TNS = $tns (total negative slack)"
     set signoff_pass 0
 } else {
diff --git a/9_Firmware/9_2_FPGA/scripts/build18_production.tcl b/9_Firmware/9_2_FPGA/scripts/build18_production.tcl
index 0feef68..18b0486 100644
--- a/9_Firmware/9_2_FPGA/scripts/build18_production.tcl
+++ b/9_Firmware/9_2_FPGA/scripts/build18_production.tcl
@@ -331,13 +331,14 @@ puts $summary_fh "Impl Time:       ${impl_elapsed}s"
 puts $summary_fh "Bitstream Time:  ${bit_elapsed}s"
 puts $summary_fh ""
 
-# Extract key timing numbers
+# Extract key timing numbers — use catch to handle empty STATS properties
+# (Vivado 2025.2 may return empty strings after write_bitstream auto-launch)
 puts $summary_fh "--- Timing ---"
-set wns [get_property STATS.WNS [current_design]]
-set tns [get_property STATS.TNS [current_design]]
-set whs [get_property STATS.WHS [current_design]]
-set ths [get_property STATS.THS [current_design]]
-set fail_ep [get_property STATS.TPWS [current_design]]
+if {[catch {set wns [get_property STATS.WNS [current_design]]}] || $wns eq ""} { set wns "N/A" }
+if {[catch {set tns [get_property STATS.TNS [current_design]]}] || $tns eq ""} { set tns "N/A" }
+if {[catch {set whs [get_property STATS.WHS [current_design]]}] || $whs eq ""} { set whs "N/A" }
+if {[catch {set ths [get_property STATS.THS [current_design]]}] || $ths eq ""} { set ths "N/A" }
+if {[catch {set fail_ep [get_property STATS.TPWS [current_design]]}] || $fail_ep eq ""} { set fail_ep "N/A" }
 puts $summary_fh "  WNS:  $wns ns"
 puts $summary_fh "  TNS:  $tns ns"
 puts $summary_fh "  WHS:  $whs ns"
@@ -376,19 +377,25 @@ puts $summary_fh ""
 # Signoff
 puts $summary_fh "--- Final Signoff ---"
 set signoff_pass 1
-if {$wns < 0} {
+if {![string is double -strict $wns]} {
+    puts $summary_fh "  WARN: WNS = N/A (timing stats unavailable — check reports)"
+} elseif {$wns < 0} {
     puts $summary_fh "  FAIL: WNS = $wns (negative slack)"
     set signoff_pass 0
 } else {
     puts $summary_fh "  PASS: WNS = $wns ns (no setup violations)"
 }
-if {$whs < 0} {
+if {![string is double -strict $whs]} {
+    puts $summary_fh "  WARN: WHS = N/A (timing stats unavailable — check reports)"
+} elseif {$whs < 0} {
     puts $summary_fh "  FAIL: WHS = $whs (hold violation)"
     set signoff_pass 0
 } else {
     puts $summary_fh "  PASS: WHS = $whs ns (no hold violations)"
 }
-if {$tns != 0} {
+if {![string is double -strict $tns]} {
+    puts $summary_fh "  WARN: TNS = N/A (timing stats unavailable — check reports)"
+} elseif {$tns != 0} {
     puts $summary_fh "  FAIL: TNS = $tns (total negative slack)"
     set signoff_pass 0
 } else {
diff --git a/9_Firmware/9_2_FPGA/scripts/build19_mmcm.tcl b/9_Firmware/9_2_FPGA/scripts/build19_mmcm.tcl
index c20f2bb..e23350b 100644
--- a/9_Firmware/9_2_FPGA/scripts/build19_mmcm.tcl
+++ b/9_Firmware/9_2_FPGA/scripts/build19_mmcm.tcl
@@ -322,21 +322,30 @@ puts $summary_fh "Impl Time:       ${impl_elapsed}s"
 puts $summary_fh "Bitstream Time:  ${bit_elapsed}s"
 puts $summary_fh ""
 
-# Extract key timing numbers
+# Extract key timing numbers — use catch to handle empty STATS properties
+# (Vivado 2025.2 may return empty strings after write_bitstream auto-launch)
 puts $summary_fh "--- Timing ---"
-set wns [get_property STATS.WNS [current_design]]
-set tns [get_property STATS.TNS [current_design]]
-set whs [get_property STATS.WHS [current_design]]
-set ths [get_property STATS.THS [current_design]]
-set fail_ep [get_property STATS.TPWS [current_design]]
+if {[catch {set wns [get_property STATS.WNS [current_design]]}] || $wns eq ""} { set wns "N/A" }
+if {[catch {set tns [get_property STATS.TNS [current_design]]}] || $tns eq ""} { set tns "N/A" }
+if {[catch {set whs [get_property STATS.WHS [current_design]]}] || $whs eq ""} { set whs "N/A" }
+if {[catch {set ths [get_property STATS.THS [current_design]]}] || $ths eq ""} { set ths "N/A" }
+if {[catch {set fail_ep [get_property STATS.TPWS [current_design]]}] || $fail_ep eq ""} { set fail_ep "N/A" }
 puts $summary_fh "  WNS:  $wns ns"
 puts $summary_fh "  TNS:  $tns ns"
 puts $summary_fh "  WHS:  $whs ns"
 puts $summary_fh "  THS:  $ths ns"
 puts $summary_fh ""
 puts $summary_fh "  Build 18 Baseline: WNS = +0.062 ns, WHS = +0.059 ns"
-puts $summary_fh "  Delta WNS: [expr {$wns - 0.062}] ns"
-puts $summary_fh "  Delta WHS: [expr {$whs - 0.059}] ns"
+if {[string is double -strict $wns]} {
+    puts $summary_fh "  Delta WNS: [expr {$wns - 0.062}] ns"
+} else {
+    puts $summary_fh "  Delta WNS: N/A (timing stats unavailable)"
+}
+if {[string is double -strict $whs]} {
+    puts $summary_fh "  Delta WHS: [expr {$whs - 0.059}] ns"
+} else {
+    puts $summary_fh "  Delta WHS: N/A (timing stats unavailable)"
+}
 puts $summary_fh ""
 
 # Extract utilization
@@ -380,19 +389,25 @@ puts $summary_fh ""
 # Signoff
 puts $summary_fh "--- Final Signoff ---"
 set signoff_pass 1
-if {$wns < 0} {
+if {![string is double -strict $wns]} {
+    puts $summary_fh "  WARN: WNS = N/A (timing stats unavailable — check reports)"
+} elseif {$wns < 0} {
     puts $summary_fh "  FAIL: WNS = $wns (negative slack)"
     set signoff_pass 0
 } else {
     puts $summary_fh "  PASS: WNS = $wns ns (no setup violations)"
 }
-if {$whs < 0} {
+if {![string is double -strict $whs]} {
+    puts $summary_fh "  WARN: WHS = N/A (timing stats unavailable — check reports)"
+} elseif {$whs < 0} {
     puts $summary_fh "  FAIL: WHS = $whs (hold violation)"
     set signoff_pass 0
 } else {
     puts $summary_fh "  PASS: WHS = $whs ns (no hold violations)"
 }
-if {$tns != 0} {
+if {![string is double -strict $tns]} {
+    puts $summary_fh "  WARN: TNS = N/A (timing stats unavailable — check reports)"
+} elseif {$tns != 0} {
     puts $summary_fh "  FAIL: TNS = $tns (total negative slack)"
     set signoff_pass 0
 } else {
@@ -413,11 +428,11 @@ if {[file exists $bit_src]} {
 puts $summary_fh ""
 
 # Timing regression check vs Build 18
-if {$wns < 0.062} {
+if {[string is double -strict $wns] && $wns < 0.062} {
     puts $summary_fh "  *** WARNING: WNS REGRESSED vs Build 18 (was +0.062 ns, now $wns ns) ***"
     puts $summary_fh "  *** Consider reverting MMCM changes per revert-safety policy ***"
 }
-if {$whs < 0.059} {
+if {[string is double -strict $whs] && $whs < 0.059} {
     puts $summary_fh "  *** WARNING: WHS REGRESSED vs Build 18 (was +0.059 ns, now $whs ns) ***"
 }
 
diff --git a/9_Firmware/9_2_FPGA/scripts/build20_mmcm_creg.tcl b/9_Firmware/9_2_FPGA/scripts/build20_mmcm_creg.tcl
index 607c014..8b34da7 100644
--- a/9_Firmware/9_2_FPGA/scripts/build20_mmcm_creg.tcl
+++ b/9_Firmware/9_2_FPGA/scripts/build20_mmcm_creg.tcl
@@ -326,13 +326,14 @@ puts $summary_fh "Impl Time:       ${impl_elapsed}s"
 puts $summary_fh "Bitstream Time:  ${bit_elapsed}s"
 puts $summary_fh ""
 
-# Extract key timing numbers
+# Extract key timing numbers — use catch to handle empty STATS properties
+# (Vivado 2025.2 may return empty strings after write_bitstream auto-launch)
 puts $summary_fh "--- Timing ---"
-set wns [get_property STATS.WNS [current_design]]
-set tns [get_property STATS.TNS [current_design]]
-set whs [get_property STATS.WHS [current_design]]
-set ths [get_property STATS.THS [current_design]]
-set fail_ep [get_property STATS.TPWS [current_design]]
+if {[catch {set wns [get_property STATS.WNS [current_design]]}] || $wns eq ""} { set wns "N/A" }
+if {[catch {set tns [get_property STATS.TNS [current_design]]}] || $tns eq ""} { set tns "N/A" }
+if {[catch {set whs [get_property STATS.WHS [current_design]]}] || $whs eq ""} { set whs "N/A" }
+if {[catch {set ths [get_property STATS.THS [current_design]]}] || $ths eq ""} { set ths "N/A" }
+if {[catch {set fail_ep [get_property STATS.TPWS [current_design]]}] || $fail_ep eq ""} { set fail_ep "N/A" }
 puts $summary_fh "  WNS:  $wns ns"
 puts $summary_fh "  TNS:  $tns ns"
 puts $summary_fh "  WHS:  $whs ns"
@@ -340,8 +341,16 @@ puts $summary_fh "  THS:  $ths ns"
 puts $summary_fh ""
 puts $summary_fh "  Build 18 Baseline: WNS = +0.062 ns, WHS = +0.059 ns"
 puts $summary_fh "  Build 19 (FAILED): WNS = -0.011 ns, WHS = +0.055 ns"
-puts $summary_fh "  Delta WNS vs B18: [expr {$wns - 0.062}] ns"
-puts $summary_fh "  Delta WHS vs B18: [expr {$whs - 0.059}] ns"
+if {[string is double -strict $wns]} {
+    puts $summary_fh "  Delta WNS vs B18: [expr {$wns - 0.062}] ns"
+} else {
+    puts $summary_fh "  Delta WNS vs B18: N/A (timing stats unavailable)"
+}
+if {[string is double -strict $whs]} {
+    puts $summary_fh "  Delta WHS vs B18: [expr {$whs - 0.059}] ns"
+} else {
+    puts $summary_fh "  Delta WHS vs B18: N/A (timing stats unavailable)"
+}
 puts $summary_fh ""
 
 # Extract utilization
@@ -387,19 +396,25 @@ puts $summary_fh ""
 # Signoff
 puts $summary_fh "--- Final Signoff ---"
 set signoff_pass 1
-if {$wns < 0} {
+if {![string is double -strict $wns]} {
+    puts $summary_fh "  WARN: WNS = N/A (timing stats unavailable — check reports)"
+} elseif {$wns < 0} {
     puts $summary_fh "  FAIL: WNS = $wns (negative slack)"
     set signoff_pass 0
 } else {
     puts $summary_fh "  PASS: WNS = $wns ns (no setup violations)"
 }
-if {$whs < 0} {
+if {![string is double -strict $whs]} {
+    puts $summary_fh "  WARN: WHS = N/A (timing stats unavailable — check reports)"
+} elseif {$whs < 0} {
     puts $summary_fh "  FAIL: WHS = $whs (hold violation)"
     set signoff_pass 0
 } else {
     puts $summary_fh "  PASS: WHS = $whs ns (no hold violations)"
 }
-if {$tns != 0} {
+if {![string is double -strict $tns]} {
+    puts $summary_fh "  WARN: TNS = N/A (timing stats unavailable — check reports)"
+} elseif {$tns != 0} {
     puts $summary_fh "  FAIL: TNS = $tns (total negative slack)"
     set signoff_pass 0
 } else {
@@ -420,11 +435,11 @@ if {[file exists $bit_src]} {
 puts $summary_fh ""
 
 # Timing regression check vs Build 18
-if {$wns < 0.062} {
+if {[string is double -strict $wns] && $wns < 0.062} {
     puts $summary_fh "  *** WARNING: WNS REGRESSED vs Build 18 (was +0.062 ns, now $wns ns) ***"
     puts $summary_fh "  *** Review critical paths — CREG fix may not have helped ***"
 }
-if {$whs < 0.059} {
+if {[string is double -strict $whs] && $whs < 0.059} {
     puts $summary_fh "  *** WARNING: WHS REGRESSED vs Build 18 (was +0.059 ns, now $whs ns) ***"
 }
 
diff --git a/9_Firmware/9_2_FPGA/scripts/build21_fft_e2e.tcl b/9_Firmware/9_2_FPGA/scripts/build21_fft_e2e.tcl
index 2733bbd..f73ae11 100644
--- a/9_Firmware/9_2_FPGA/scripts/build21_fft_e2e.tcl
+++ b/9_Firmware/9_2_FPGA/scripts/build21_fft_e2e.tcl
@@ -335,13 +335,14 @@ puts $summary_fh "Impl Time:       ${impl_elapsed}s"
 puts $summary_fh "Bitstream Time:  ${bit_elapsed}s"
 puts $summary_fh ""
 
-# Extract key timing numbers
+# Extract key timing numbers — use catch to handle empty STATS properties
+# (Vivado 2025.2 may return empty strings after write_bitstream auto-launch)
 puts $summary_fh "--- Timing ---"
-set wns [get_property STATS.WNS [current_design]]
-set tns [get_property STATS.TNS [current_design]]
-set whs [get_property STATS.WHS [current_design]]
-set ths [get_property STATS.THS [current_design]]
-set fail_ep [get_property STATS.TPWS [current_design]]
+if {[catch {set wns [get_property STATS.WNS [current_design]]}] || $wns eq ""} { set wns "N/A" }
+if {[catch {set tns [get_property STATS.TNS [current_design]]}] || $tns eq ""} { set tns "N/A" }
+if {[catch {set whs [get_property STATS.WHS [current_design]]}] || $whs eq ""} { set whs "N/A" }
+if {[catch {set ths [get_property STATS.THS [current_design]]}] || $ths eq ""} { set ths "N/A" }
+if {[catch {set fail_ep [get_property STATS.TPWS [current_design]]}] || $fail_ep eq ""} { set fail_ep "N/A" }
 puts $summary_fh "  WNS:  $wns ns"
 puts $summary_fh "  TNS:  $tns ns"
 puts $summary_fh "  WHS:  $whs ns"
@@ -349,8 +350,16 @@ puts $summary_fh "  THS:  $ths ns"
 puts $summary_fh ""
 puts $summary_fh "  Build 20 Baseline: WNS = +0.426 ns, WHS = +0.058 ns"
 puts $summary_fh "  Gap 2 Build (ref): WNS = +0.078 ns, WHS = +0.054 ns"
-puts $summary_fh "  Delta WNS vs B20: [expr {$wns - 0.426}] ns"
-puts $summary_fh "  Delta WHS vs B20: [expr {$whs - 0.058}] ns"
+if {[string is double -strict $wns]} {
+    puts $summary_fh "  Delta WNS vs B20: [expr {$wns - 0.426}] ns"
+} else {
+    puts $summary_fh "  Delta WNS vs B20: N/A (timing stats unavailable)"
+}
+if {[string is double -strict $whs]} {
+    puts $summary_fh "  Delta WHS vs B20: [expr {$whs - 0.058}] ns"
+} else {
+    puts $summary_fh "  Delta WHS vs B20: N/A (timing stats unavailable)"
+}
 puts $summary_fh ""
 
 # Extract utilization
@@ -396,19 +405,25 @@ puts $summary_fh ""
 # Signoff
 puts $summary_fh "--- Final Signoff ---"
 set signoff_pass 1
-if {$wns < 0} {
+if {![string is double -strict $wns]} {
+    puts $summary_fh "  WARN: WNS = N/A (timing stats unavailable — check reports)"
+} elseif {$wns < 0} {
     puts $summary_fh "  FAIL: WNS = $wns (negative slack)"
     set signoff_pass 0
 } else {
     puts $summary_fh "  PASS: WNS = $wns ns (no setup violations)"
 }
-if {$whs < 0} {
+if {![string is double -strict $whs]} {
+    puts $summary_fh "  WARN: WHS = N/A (timing stats unavailable — check reports)"
+} elseif {$whs < 0} {
     puts $summary_fh "  FAIL: WHS = $whs (hold violation)"
     set signoff_pass 0
 } else {
     puts $summary_fh "  PASS: WHS = $whs ns (no hold violations)"
 }
-if {$tns != 0} {
+if {![string is double -strict $tns]} {
+    puts $summary_fh "  WARN: TNS = N/A (timing stats unavailable — check reports)"
+} elseif {$tns != 0} {
     puts $summary_fh "  FAIL: TNS = $tns (total negative slack)"
     set signoff_pass 0
 } else {
@@ -429,11 +444,11 @@ if {[file exists $bit_src]} {
 puts $summary_fh ""
 
 # Timing regression check vs Build 20
-if {$wns < 0.078} {
+if {[string is double -strict $wns] && $wns < 0.078} {
     puts $summary_fh "  *** WARNING: WNS REGRESSED below Gap 2 build (was +0.078 ns, now $wns ns) ***"
     puts $summary_fh "  *** Review critical paths — FFT opts or RTL fixes may have introduced new timing pressure ***"
 }
-if {$whs < 0.054} {
+if {[string is double -strict $whs] && $whs < 0.054} {
     puts $summary_fh "  *** WARNING: WHS REGRESSED below Gap 2 build (was +0.054 ns, now $whs ns) ***"
 }