fix(stm32wl): smaller MAX_RX_TOPHONE and PACKETHISTORY_MAX on stm32wl

[t-miura]

Reducing MAX_RX_TOPHONE and PACKETHISTORY_MAX for stm32wl platform, guarded by ARCH_STM32WL,
to save/maintain some free RAM/heap while ensuring client connection via its serial working.

for MAX_RX_TO_PHONE it's fixed to 8 and it's open question that number is enough or not.
while PACKETHISTORY_MAX is tied to MAX_NUM_NODES which is currently set to 10 for stm32wl.

related PRs(to be added):

• fix: defensive fixes for packet/routing related memory leakages #11223

🤝 Attestations

• I have tested that my proposed changes behave as described.
• I have tested that my proposed changes do not cause any obvious regressions on the following devices:
  • Heltec (Lora32) V3
  • LilyGo T-Deck
  • LilyGo T-Beam
  • RAK WisBlock 4631
  • Seeed Studio T-1000E tracker card
  • Other (please specify below)
    • Seeed Wio-E5 (STM32WL)
    • Wiznet W5500-EVB-Pico2 (RP2350, paired with Wio-SX1262)

Summary by CodeRabbit

• Performance Improvements
  • Optimized packet handling for STM32WL devices by reducing the maximum queued packets and packet history size.
  • Helps lower memory usage while retaining support for the expected number of network nodes.

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📝 Walkthrough

Walkthrough

STM32WL builds now use MAX_RX_TOPHONE value 8 and PACKETHISTORY_MAX value MAX_NUM_NODES * 2. Other platform limits remain unchanged.

Changes

STM32WL resource limits

Layer / File(s)	Summary
Platform resource configuration src/mesh/mesh-pb-constants.h	STM32WL uses 8 for MAX_RX_TOPHONE and MAX_NUM_NODES * 2 for PACKETHISTORY_MAX.

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

Suggested labels: bugfix

Suggested reviewers: caveman99, thebentern, nomdetom

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the STM32WL-specific reductions to MAX_RX_TOPHONE and PACKETHISTORY_MAX.
Description check	✅ Passed	The description explains the purpose, platform scope, implementation, testing, and attestations, with only a non-critical related-PR placeholder remaining.
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.

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[t-miura]

@caveman99
sorry, the previous changes for Router.cpp was not required(did wrong cherry-pick),
reverted, and the only file this PR will change is src/mesh/mesh-pb-constants.h

[t-miura]

@coderabbitai full review

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✅ Action performed

Full review finished.

[coderabbitai]

🧹 Nitpick comments (1)

src/mesh/mesh-pb-constants.h (1)

32-35: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Shorten the MAX_RX_TOPHONE rationale comment.

Keep this comment to one or two lines. Retain only the non-obvious RAM rationale.

As per coding guidelines, comments must normally be one or two lines and must explain only non-obvious rationale.

Proposed comment reduction

-// Each slot is a ~340 B MeshPacket in the static pool (Router.cpp MAX_PACKETS_STATIC), so 32 slots
-// cost ~11 KB of .bss on the RAM-tightest platform (2.8.0 field reports: 99% heap). 16 still doubles
-// the 8 classic ESP32 has shipped with for years; drops start when a stalled phone/serial client has
-// 16 packets queued.
+// Keep 16 slots on RAM-tight NRF52840 boards to limit static MeshPacket memory.
+// A stalled phone/serial client can fill the queue and cause drops.

🤖 Prompt for 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.

In `@src/mesh/mesh-pb-constants.h` around lines 32 - 35, Shorten the rationale
comment above MAX_RX_TOPHONE to one or two lines, retaining only the non-obvious
RAM usage rationale for the slot count and removing historical, platform, and
operational details.

Source: Coding guidelines

🤖 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.

Nitpick comments:
In `@src/mesh/mesh-pb-constants.h`:
- Around line 32-35: Shorten the rationale comment above MAX_RX_TOPHONE to one
or two lines, retaining only the non-obvious RAM usage rationale for the slot
count and removing historical, platform, and operational details.

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ℹ️ Review info

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📥 Commits

Reviewing files that changed from the base of the PR and between b8dee13 and 3f04401.

📒 Files selected for processing (1)

• src/mesh/mesh-pb-constants.h