[ODevStudio]

Summary

• Advance the source base to 3.1.16; regenerate main custom metadata and verify 3.1.16-main-custom while retaining 3.1.15-custom for the existing stable tag.
• Update AI guidance, user documentation, and the release checkpoint for changes since v3.1.15.
• Define complete release work: main version advancement, signed official WiFi OTA, tagged custom builds, service activation, and the new public stable/default.

Safe Release Ordering

This is the pre-tag release PR. It intentionally does not enable a missing v3.1.16 backend ref or change the live public default before publication. The equivalent post-tag custom/default rollout is prepared separately; merging a missing-tag ref into the live main builder would break existing hosted builds.

After required CI and an authorized merge, pin the resulting main commit for the immutable tag and signed draft/publication workflows. Then activate and verify tagged custom support and the published 3.1.16 default, retaining older refs and recovery assets. Official/custom OTA signing, verification, keys, and partition layout retain the 3.1.15 flow. The release workflow now defaults its previous-stable input to v3.1.15; the runtime guard and v3.1.13 catalog history floor remain unchanged.

Validation

• Independent subagent re-review: no remaining pre-tag PR blockers after correcting the main version and metadata.
• python tools/test_ai_docs_contract.py: passed.
• python tools/test_plugin_catalog.py: passed.
• Configurator and Worker Node suites: 34 passed, none skipped.
• python tools/test_release_workflow_contract.py: passed for the corrected previous-stable default.
• Raw diff/whitespace checks: passed.
• Baseline firmware/native/energy CI and local Pressensor/combined firmware plus LittleFS evidence are retained with their original source SHA in the checkpoint; these are not exact signed release-byte or final-PR CI results.

Remaining Release Gates

• Required CI on this PR.
• Separate authorization for merge, tagging, signed draft/publication, and service/default deployment.
• Exact signed-byte hardware acceptance and production older-to-newer OTA verification, or explicit acceptance of untested paths.

No release tag, release workflow dispatch, publication, deployment, scale assignment, or flashing is performed by this PR.

Checkpoint: docs/release-3.1.16-preparation.md.

Coordinated Release PRs

The complete code delivery is now available for review; the later phases are remote draft PRs rather than local-only branches.

Phase	PR	Hold condition
Version, documentation, and workflow preparation	#278	Required current-head CI and authorized merge
Tagged custom support	#279 (draft)	#278 merged, real v3.1.16 tag on the approved main commit, branch refreshed/retargeted against that tagged main
Public 3.1.16 selector/default	#280 (draft)	Official stable/latest publication, deployed Worker support, and a verified real production-signed tagged custom build

The stack bases are deliberate: #279 targets this PR's branch, and #280 targets backend support, so each phase has a focused diff. After dependencies merge, refresh/retarget against the actual main history before subsequent merges, particularly after squash merges. Neither draft enables auto-merge.

All three workflows on original preparation head 2bc688c passed. The current heads must satisfy their own checks; these CI results do not verify a hosted production-signed 3.1.16-custom build, signed release bytes on hardware, or a production OTA update.

The release is still not published or deployed. Creating the PRs fixes the missing reviewable-delivery gap; the documented signing, hardware, publication, service, and live-default acceptance gates remain open.