Added support for C3 JAM SDK

[DrEverr]

Add C3 JAM SDK (jamsdk)

Adding C3 as a new SDK option for building JAM services and authorizers via jamc3.

Why a new SDK?

The other SDKs are built with their own scope and priorities, which is fine, but I wanted something I fully own end-to-end, designed the way I think a JAM SDK should work. On top of that, I've been getting into C3 and it turns out to be a really nice fit for this kind of work:

• No runtime, no GC. C3 compiles straight to native code with zero implicit allocations — exactly what you want when targeting PolkaVM, without writing actual C.
• Cross-compiling to RISC-V. c3c has first-class rv64imac support with no-stdlib/no-libc out of the box. No toolchain wrestling.
• Native C ABI. Host function bindings are clean extern fn declarations — no FFI wrappers, no unsafe blocks. All 27 host calls are one-liners.
• Tiny blobs. No hidden runtime means .jam output is small and deterministic. Every byte counts on-chain.
• Modern where it matters. Optional types, faults, defer, modules, slices — safety without the compile-time tax or binary bloat.

What's in the box

• Full SDK library (jamc3.c3l) — all 27 host functions, Gray Paper types, high-level service/storage APIs, Appendix C codecs
• Entry point dispatch for services (refine + accumulate) and authorizers (is_authorized)
• Build pipeline: C3 → RISC-V → ELF → .polkavm → .jam
• Patched polkavm-to-jam converter (works with polkatool 0.29+)
• Docker image with everything bundled: ghcr.io/dreverr/jamc3
• Four examples: hello-world, storage-demo, simple-auth, fibonacci

Links

• https://github.com/DrEverr/jamc3
• https://github.com/DrEverr/jamc3.c3l
• https://c3-lang.org/

[coderabbitai]

📝 Walkthrough

Walkthrough

This pull request adds support for a new "c3sdk" template in the CLI creation command. The changes extend the template options and add corresponding SDK configuration for version 1.0.2 with build and test settings.

Changes

Cohort / File(s)	Summary
CLI Template Addition bin/cli/src/commands/create-command.ts	Added "c3sdk" template option to the Template union type and created a new TARGETS mapping entry linking "c3sdk" to "jammin-create/jammin-create-c3sdk".
SDK Configuration packages/jammin-sdk/config/sdk-configs.ts	Added new SDK configuration entry "c3sdk-1.0.2" with image, build, and test field definitions.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• Ajanta SDK support #81: Modifies the same CLI and SDK configuration files with similar template and TARGETS mapping additions.

Suggested reviewers

• tomusdrw
• skoszuta

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: adding support for a new C3 JAM SDK option to the codebase.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Description check	✅ Passed	The pull request description clearly relates to the changeset, describing the addition of C3 SDK support with detailed motivation and technical context.

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✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch maso-c3-jamsdk

📝 Coding Plan

• Generate coding plan for human review comments

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[coderabbitai]

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@packages/jammin-sdk/config/sdk-configs.ts`:
- Around line 25-29: The new SDK entry "c3sdk-1.0.2" in the exported config
object is missing the trailing comma after its closing brace and needs
formatting; update the object literal for the key "c3sdk-1.0.2" to include the
trailing comma after the block (after the closing brace) and then run the
project's formatter/biome to reformat the file so the entry matches project
style (ensure properties image, build, and test remain intact).
- Line 26: Replace the tag-only image value image:
"ghcr.io/dreverr/jamsdk:1.0.2" with a digest-pinned reference (e.g.
ghcr.io/dreverr/jamsdk:1.0.2@sha256:<actual-digest>) following the same pattern
used by jambrains-1cfc41c so the C3 toolchain image is immutable; also add the
missing trailing comma after the closing } of that object to satisfy Biome
formatting.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 9327845e-ea44-4f4e-965a-3412ae293538

📥 Commits

Reviewing files that changed from the base of the PR and between ba21a2c and bbc7db7.

📒 Files selected for processing (2)

• bin/cli/src/commands/create-command.ts
• packages/jammin-sdk/config/sdk-configs.ts