feat: halve the record buffer now the store holds the backlog

[DavidCozens]

Pull request

What this stage adds

The ring is sized in records, so doubling the message cap doubled its cost. Four
records is enough to absorb a burst logged while the service task is sending; the
store, not the ring, is what holds a backlog.

Flash +11,980 B (unchanged)
RAM +7,384 B (-2,056)
Log stack +704 B (unchanged)
Service +992 B (unchanged)

Static RAM is the only figure that moves, and it is exactly four records at the cap
plus a two-byte length prefix each. Nothing else is affected: the ring bounds how
many records can be in flight, not how large one may be.

Taken with the cap rise, the pair costs 248 bytes. The ring ends up 8 bytes smaller
than it was before the cap moved — four records at 512 is less than eight at 256 —
so what is actually being paid for is the store's single record buffer, which
follows the cap and cannot be halved.

Files

 README.md                     | 15 ++++++++-------
 app/syslog/Syslog.c           |  7 ++++---
 measurements/buffer-halve.csv | 13 +++++++++++++
 measurements/stages.tsv       |  1 +
 run-report.md                 | 26 +++++++++++++-------------
 5 files changed, 39 insertions(+), 23 deletions(-)

Checklist

• The diff is application-only — no change to board bring-up, config headers, or build infra.
• measurements/buffer-halve.csv committed.
• Row added to measurements/stages.tsv.
• README regenerated: python3 scripts/gen-cost-table.py.
• ./run.sh green (build + QEMU + baseline self-check) — run-report.md committed.

---

Context for review: 14 of 21 sequential single-commit PRs replaying the integration on top of the Baseline root. Each lands green and reviewed before the next is built on it, because a change to an early commit would force every commit above it to be re-run and re-measured.

Summary by CodeRabbit

• Improvements

  • Reduced the system log buffer size from eight records to four, lowering static memory usage while retaining capacity for short bursts when log delivery is busy.
  • Updated resource-usage measurements to reflect the smaller buffer configuration.

• Documentation

  • Updated configuration guidance, cost figures, and performance tables to describe the smaller ring setting.
  • Refreshed validation and measurement reports with results from the updated configuration.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: a4071a0f-c469-4a2f-bb80-6f490c8c7d46

📥 Commits

Reviewing files that changed from the base of the PR and between 9fb81d6 and b610b5e.

⛔ Files ignored due to path filters (2)

• measurements/buffer-halve.csv is excluded by !**/*.csv
• measurements/stages.tsv is excluded by !**/*.tsv

📒 Files selected for processing (3)

• README.md
• app/syslog/Syslog.c
• run-report.md

---

📝 Walkthrough

Walkthrough

The syslog circular buffer is reduced from eight records to four. README stage costs, aggregate resource deltas, and the generated run report are updated for the smaller-ring configuration.

Changes

Smaller ring stage

Layer / File(s)	Summary
Reduce syslog ring capacity app/syslog/Syslog.c	Changes SYSLOG_BUFFER_RECORDS from eight to four and documents the ring’s burst-buffering role.
Update measurements and documentation README.md, run-report.md	Replaces the larger-cap stage with the smaller-ring stage and updates cost figures, run measurements, size totals, captured logs, and self-check assertions.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• cososo-ltd/solid-syslog-example#10: Adds the logger implementation whose circular buffer is resized here.
• cososo-ltd/solid-syslog-example#13: Covers the buffered circular-queue logging implementation using the original eight-record size.
• cososo-ltd/solid-syslog-example#18: Directly relates to changing SYSLOG_BUFFER_RECORDS from eight to four.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: reducing the syslog record buffer because the store now holds backlog.
Description check	✅ Passed	The description matches the template and includes the required stage summary and checklist items with all checks filled.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch stage/buffer-halve

---

_{Comment @coderabbitai help to get the list of available commands.}