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Upstream Sync

heliaRT is periodically replanted on upstream LiteRT for Micro (tensorflow/tflite-micro) main. This page explains the process and the blast-radius reduction philosophy.

How It Works

gitGraph
    commit id: "main (heliaRT)"
    branch upstream-sync
    commit id: "fetch tflite-micro/main"
    commit id: "resolve conflicts"
    commit id: "re-run disable_upstream_workflows.sh"
    checkout main
    merge upstream-sync id: "squash-merge"
    commit id: "continue development"

Step-by-Step

  1. Fetch upstream — pull the latest tflite-micro main into a fresh sync branch.

  2. Resolve conflicts — because Ambiq additions live in isolated directories (kernels/helia/, ci/, zephyr/), conflicts are typically limited to:

    • Makefile.inc (kernel lists)
    • BUILD files
    • Shared infrastructure files

  3. Re-disable upstream workflows — run the idempotent script:

    ./ci/disable_upstream_workflows.sh

    This uses the GitHub API to disable upstream workflow files that would otherwise run on push. The YAML files remain unedited.

  4. Run CI — verify the full test matrix passes.

  5. Squash-merge — merge into main with a single feat: upstream sync commit.

Blast-Radius Philosophy

The goal is to minimise the surface area where heliaRT touches upstream code:

Strategy Why
Ambiq kernels in kernels/helia/ Doesn't edit any upstream kernel files
helia.inc as an ext_lib Uses the existing OPTIMIZED_KERNEL_DIR extension point
Upstream workflows disabled via API Avoids editing upstream YAML files
Dependabot ignores for upstream actions Prevents noise from action version bumps we don't control
third_party_static/ for vendored headers Avoids submodule conflicts

The result

Most upstream syncs resolve with zero or near-zero conflicts because Ambiq additions don't overlap with upstream changes.

Post-Sync Checklist

  • Run ./ci/disable_upstream_workflows.sh to re-disable any new upstream workflows
  • Verify operator coverage matrix is still accurate
  • Run full CI matrix
  • Check that Zephyr CMakeLists.txt kernel list matches any new/removed upstream kernels
  • Update CHANGELOG.md with the sync details

Next Steps