feat: raise the message cap to fit the grown record

[DavidCozens]

Pull request

What this stage adds

Three SD-ELEMENTs put the record at 245 bytes, but sequenceId and sysUpTime are
both 32-bit counters: at full width the same record is 261 bytes, past the 256-byte
cap and into truncation. The cap doubles to 512.

Flash +11,980 B (+8 on the previous stage)
RAM +9,440 B (+2,304)
Log stack +704 B (+256)
Service +992 B (+256)

The cap is the largest single demand the formatter makes of whichever task calls
it, so both stacks rise by exactly the difference — 568 to 824 on the log task, 788
to 1,044 on the service task. Both seams were sized at 2 KiB when the send moved,
so they absorb it and no RAM moves with them.

The RAM that does move accounts for itself exactly. The ring is eight records at
the cap plus a two-byte length prefix each, so it grows 2,048. The store keeps one
record buffer of cap plus integrity trailer plus framing, so it grows 256. That is
the whole 2,304.

The store is otherwise unaffected. SOLIDSYSLOG_FILE_DEFAULT_BLOCK_SIZE must hold
one worst-case record — cap plus integrity trailer plus five framing bytes, 549
here — and at 8192 it has room to spare.

Files

 README.md                          | 15 +++++++++------
 app/config/solid_syslog_tunables.h | 10 ++++------
 measurements/cap-rise.csv          | 13 +++++++++++++
 measurements/stages.tsv            |  1 +
 run-report.md                      | 38 +++++++++++++++++++-------------------
 5 files changed, 46 insertions(+), 31 deletions(-)

Checklist

• The diff is application-only — no change to board bring-up, config headers, or build infra.
• measurements/cap-rise.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: 13 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

• New Features

  • Increased the maximum syslog message size from 256 to 512 bytes, allowing longer records (with over-length messages truncated rather than dropped).

• Documentation

  • Updated README stage guidance to describe the larger message-cap behavior and refreshed related cost comparisons.
  • Refreshed run-report measurements and self-check assertions to match the cap-rise build results.

[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: 98ab90ad-4493-4ade-bf18-49ee42d961c9

📥 Commits

Reviewing files that changed from the base of the PR and between bb51efb and 3746c59.

⛔ Files ignored due to path filters (2)

• measurements/cap-rise.csv is excluded by !**/*.csv
• measurements/stages.tsv is excluded by !**/*.tsv

📒 Files selected for processing (3)

• README.md
• app/config/solid_syslog_tunables.h
• run-report.md

🚧 Files skipped from review as they are similar to previous changes (2)

• README.md
• run-report.md

---

📝 Walkthrough

Walkthrough

The compile-time SolidSyslog message cap increases from 256U to 512U. README stage and cost-table entries, along with cap-rise measurements, baseline checks, and self-check output, are updated to match.

Changes

Syslog message cap update

Layer / File(s)	Summary
Update message cap app/config/solid_syslog_tunables.h	The SOLIDSYSLOG_MAX_MESSAGE_SIZE override changes from 256U to 512U.
Update cap-rise documentation and measurements README.md, run-report.md	Stage descriptions, cost figures, run measurements, baseline checks, BOOT output, and self-check assertions are updated for the cap-rise run.

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

Possibly related PRs

• cososo-ltd/solid-syslog-example#10: Updates the same message-size tunable and related cost outputs.
• cososo-ltd/solid-syslog-example#18: Contains the same 256U-to-512U message-cap change.
• cososo-ltd/solid-syslog-example#34: Modifies the same tunable with corresponding cap behavior documentation.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise and accurately summarizes the main change: increasing the message cap.
Description check	✅ Passed	The description matches the template and covers the required summary, checklist, and implementation details.
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/cap-rise

---

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

[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@app/config/solid_syslog_tunables.h`:
- Around line 7-10: Update the comment above SOLIDSYSLOG_MAX_MESSAGE_SIZE to
avoid claiming RFC 5424 interoperability for 512 bytes; explicitly describe the
cap as applying to the bundled collector, or change the constant to the minimum
standards-supported receiver size if it is intended as a general
interoperability limit.

In `@README.md`:
- Around line 19-24: Update the “Larger cap” cost description in the README to
say the cost is primarily RAM, reflecting the reported Flash increase as well as
the RAM increase. Leave the generated cost table and its markers unchanged.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: fb6fd628-adac-4972-8f74-cd105d593980

📥 Commits

Reviewing files that changed from the base of the PR and between 57262b5 and bb51efb.

⛔ Files ignored due to path filters (2)

• measurements/cap-rise.csv is excluded by !**/*.csv
• measurements/stages.tsv is excluded by !**/*.tsv

📒 Files selected for processing (3)

• README.md
• app/config/solid_syslog_tunables.h
• run-report.md