cososo-ltd · DavidCozens · Jul 29, 2026 · Jul 29, 2026
diff --git a/README.md b/README.md
@@ -10,15 +10,15 @@ It builds on a baseline that simulates the sort of device you might be adding th
 measures itself: see [docs/baseline.md](docs/baseline.md) for what the baseline is, how the
 figures are made, and how to run it.
 
-## This stage — TCP
+## This stage — Time quality
 
-The sender is a TCP stream to the collector on 5601 instead of a UDP datagram, with records framed
-by octet count as a receiver on a stream expects. A record the network drops is retransmitted
-rather than lost, and a send to a collector that is not there fails instead of quietly succeeding.
+The record gains a `timeQuality` SD-ELEMENT and a `sysUpTime` PARAM on `meta`. This device's clock
+free-runs on the tick after one reading at boot, so it reports `isSynced="0"` and the collector
+knows how far to trust the timestamp.
 
 <!-- STAGE-COST:START (generated by scripts/gen-cost-table.py — do not edit by hand) -->
 
-**Cost above baseline: Flash +7,320 B, RAM +5,856 B.**
+**Cost above baseline: Flash +7,612 B, RAM +5,880 B.**
 
 <!-- STAGE-COST:END -->
 
@@ -41,6 +41,7 @@ committed as [`run-report.md`](run-report.md), and rewritten by every stage.
 | Message cap | a bounded record size, so a long message truncates instead of being dropped | +6,032 | +1,956 |
 | Buffered | logging that returns immediately, with the send moved off the logging task | +6,788 | +5,676 |
 | TCP | records the network retransmits instead of dropping, and a send that fails when the collector is gone | +7,320 | +5,856 |
+| Time quality | a timestamp the collector knows how far to trust, and an uptime that tells a reboot from a counter wrap | +7,612 | +5,880 |
 
 *Deltas are bytes above the baseline, which is itself Flash 350,308 B, RAM 111,192 B.*
 

diff --git a/app/syslog/Syslog.c b/app/syslog/Syslog.c
@@ -14,6 +14,7 @@
 #include "SolidSyslogEndpoint.h"
 #include "SolidSyslogEndpointHost.h"
 #include "SolidSyslogFreeRtosMutex.h"
+#include "SolidSyslogFreeRtosSysUpTime.h"
 #include "SolidSyslogLwipRawAddress.h"
 #include "SolidSyslogLwipRawMarshal.h"
 #include "SolidSyslogLwipRawResolver.h"
@@ -22,6 +23,8 @@
 #include "SolidSyslogNullStore.h"
 #include "SolidSyslogStdAtomicCounter.h"
 #include "SolidSyslogStreamSender.h"
+#include "SolidSyslogTimeQuality.h"
+#include "SolidSyslogTimeQualitySd.h"
 #include "SyslogFields.h"
 
 #include "lwip/tcpip.h"
@@ -47,7 +50,16 @@ static struct SolidSyslog* s_logger = NULL;
 static uint8_t s_ring[SOLIDSYSLOG_CIRCULAR_BUFFER_RING_BYTES(SYSLOG_BUFFER_RECORDS)];
 
 /* The logger reads these on every record, so they outlive Syslog_Start. */
-static struct SolidSyslogStructuredData* s_sd[1];
+static struct SolidSyslogStructuredData* s_sd[2];
+
+/* One reading at boot, then free-running on the tick — enough to stamp a record,
+ * not synchronisation. */
+static void SyslogTimeQuality(struct SolidSyslogTimeQuality* timeQuality)
+{
+    timeQuality->TzKnown = true;
+    timeQuality->IsSynced = false;
+    timeQuality->SyncAccuracyMicroseconds = SOLIDSYSLOG_SYNC_ACCURACY_OMIT;
+}
 
 /* Bounds the connect spin so it yields instead of busy-waiting. */
 static void SyslogSleep(int milliseconds)
@@ -96,8 +108,12 @@ void Syslog_Start(void)
 
     /* One counter Increment per record formatted, so a record that never reaches
      * the collector leaves a gap in the sequence rather than no trace at all. */
-    struct SolidSyslogMetaSdConfig metaConfig = {.Counter = SolidSyslogStdAtomicCounter_Create()};
+    struct SolidSyslogMetaSdConfig metaConfig = {
+        .Counter = SolidSyslogStdAtomicCounter_Create(),
+        .GetSysUpTime = SolidSyslogFreeRtosSysUpTime_Get,
+    };
     s_sd[0] = SolidSyslogMetaSd_Create(&metaConfig);
+    s_sd[1] = SolidSyslogTimeQualitySd_Create(SyslogTimeQuality);
 
     struct SolidSyslogConfig config = {
         .Buffer = SolidSyslogCircularBuffer_Create(SolidSyslogFreeRtosMutex_Create(), s_ring, sizeof(s_ring)),

diff --git a/measurements/stages.tsv b/measurements/stages.tsv
@@ -19,3 +19,4 @@ sequence-id	Sequence numbers	every record numbered, so a gap in the sequence is
 message-cap	Message cap	a bounded record size, so a long message truncates instead of being dropped
 buffered	Buffered	logging that returns immediately, with the send moved off the logging task
 tcp	TCP	records the network retransmits instead of dropping, and a send that fails when the collector is gone
+time-quality	Time quality	a timestamp the collector knows how far to trust, and an uptime that tells a reboot from a counter wrap
diff --git a/measurements/time-quality.csv b/measurements/time-quality.csv
@@ -0,0 +1,13 @@
+# time-quality figures (bytes) — captured by scripts/run.sh (CAPTURE=1).
+# The device reads measurements/Baseline.csv as its frozen baseline and reports current-minus-Baseline.
+flash_text,357424
+flash_data,496
+static_bss,116576
+heap_used,4440
+mbedtls_peak,21352
+mbedtls_free,11416
+lwip_mem_free,7576
+lwip_pbufs_free,13
+stack_log,568
+stack_service,724
+stack_harness,2848
diff --git a/run-report.md b/run-report.md
@@ -1,4 +1,4 @@
-# solid-syslog-example — run (tcp)
+# solid-syslog-example — run (time-quality)
 
 ## Device (self-measured)
 
@@ -10,12 +10,12 @@
 [device]   first record logged: yes
 [report] --- SolidSyslog cost above baseline (simulated existing application) ---
 [report] key,current,baseline,used_above_baseline
-[report] flash_text,357140,349992,7148
-[report] flash_data,488,316,172
-[report] static_bss,116560,110876,5684
+[report] flash_text,357424,349992,7432
+[report] flash_data,496,316,180
+[report] static_bss,116576,110876,5700
 [report] heap_used,4440,4440,0
-[report] mbedtls_peak,21328,21332,-4
-[report] mbedtls_free,11440,11436,4
+[report] mbedtls_peak,21352,21332,20
+[report] mbedtls_free,11416,11436,-20
 [report] lwip_mem_free,7576,7576,0
 [report] lwip_pbufs_free,13,14,-1
 [report] stack_log,568,120,448
@@ -29,7 +29,7 @@
 
 ```text
    text	   data	    bss	    dec	    hex	filename
- 357132	    496	 116560	 474188	  73c4c	/w/build/baseline-cross/baseline.elf
+ 357416	    504	 116576	 474496	  73d80	/w/build/baseline-cross/baseline.elf
 ```
 
 ## Listeners (proved before the device ran)
@@ -47,19 +47,19 @@
 ## Collector (syslog-ng) received
 
 ```text
-wire   <134>1 2026-07-29T07:30:26.440000Z 10.0.2.15 solid-syslog-example - BOOT [meta sequenceId="1"] device started
-parsed PRIORITY=134 TIMESTAMP=2026-07-29T07:30:26+00:00 HOSTNAME=10.0.2.15 APP_NAME=solid-syslog-example PROCID= MSGID=BOOT STRUCTURED_DATA=[meta sequenceId="1"] MSG=device started
+wire   <134>1 2026-07-29T07:42:02.620000Z 10.0.2.15 solid-syslog-example - BOOT [meta sequenceId="1" sysUpTime="362"][timeQuality tzKnown="1" isSynced="0"] device started
+parsed PRIORITY=134 TIMESTAMP=2026-07-29T07:42:02+00:00 HOSTNAME=10.0.2.15 APP_NAME=solid-syslog-example PROCID= MSGID=BOOT STRUCTURED_DATA=[meta sequenceId="1" sysUpTime="362"][timeQuality tzKnown="1" isSynced="0"] MSG=device started
 ```
 
-## Self-check (vs measurements/tcp.csv)
+## Self-check (vs measurements/time-quality.csv)
 
 ```text
-  OK    flash_text: 357140 (expected 357140, Δ0)
-  OK    flash_data: 488 (expected 488, Δ0)
-  OK    static_bss: 116560 (expected 116560, Δ0)
+  OK    flash_text: 357424 (expected 357424, Δ0)
+  OK    flash_data: 496 (expected 496, Δ0)
+  OK    static_bss: 116576 (expected 116576, Δ0)
   OK    heap_used: 4440 (expected 4440, Δ0)
-  OK    mbedtls_peak: 21328 (expected 21328, Δ0)
-  OK    mbedtls_free: 11440 (expected 11440, Δ0)
+  OK    mbedtls_peak: 21352 (expected 21352, Δ0)
+  OK    mbedtls_free: 11416 (expected 11416, Δ0)
   OK    lwip_mem_free: 7576 (expected 7576, Δ0)
   OK    lwip_pbufs_free: 13 (expected 13, Δ0)
   OK    stack_log: 568 (expected 568, Δ0)