feat(cli): mops generate bindings for .did → Motoko

[Kamirus]

Motoko projects that call many principals sharing one interface (ICRC ledgers, routers, wallets) need typed actor(id) : Foo.Self without hand-writing service modules or installing didc.

mops generate bindings embeds candid_parser's Motoko bindgen (same codegen as didc bind -t mo) in the existing CLI wasm and regenerates .mo from committed .did files.

Before

# separate didc install required
didc bind -t mo candid/icrc.did > bindings/ICRC.mo

After

[bindings.ICRC]
did = "candid/icrc.did"# out = "bindings/ICRC.mo" # optional; default <dir(did)>/<name>.mo

mops generate bindings
# or ad-hoc (mops.toml optional):
mops generate bindings candid/icrc.did -o bindings/ICRC.mo

importICRC"mo:…/ICRC";
let ledger =actor (id) : ICRC.Self;

What is unchanged

• mops generate candid (Motoko → .did) is untouched.
• Single fixed-target inter-canister calls should still use canister: + --actor-env-alias (examples#1452 / #1453).
• No auto-run on build/check in v1 — explicit only.
• .didimports are rejected (flatten first). Unlike didc, we do not resolve imports via the filesystem.
• Snake_case Candid type aliases stay snake_case in Motoko until candid#729 ships; PascalCase DIDs (e.g. ICRC) already look idiomatic.

Context: dfinity/examples#1454.

[github-actions]

Cursor AI review

👍 APPROVE — looks safe to merge

Category	Assessment	Details
Summary	✅	Adds mops generate bindings to emit Motoko modules from committed .did files via embedded candid_parser Motoko bindgen, with [bindings.*] config and ad-hoc -o mode.
Code Quality	✅	Mirrors generate candid / is-candid-compatible patterns; thin wasm helper; no speculative scope.
Consistency	✅	Sibling of generate candid (flags, .mops/ refusal, no-arg = all); docs, changelog, and skills updated together.
Security	✅	Rejects writes under .mops/ and rejects .did imports rather than resolving them from the filesystem.
Tests	✅	Snapshots for main success paths; targeted assertions for errors, ad-hoc-without-toml, and invalid/import inputs.
Maintainability	✅	Clear command/helper/wasm split; config typed in types.ts; intentional v1 limits documented.

Verdict

Decision: APPROVE
Risk: Low
Reason: Additive, well-tested CLI feature that follows existing mops generate candid patterns with matching docs/changelog/skills; no backend, API version, or breaking surface changes.

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Generated for commit 1df8e29

[Kamirus]

I'd rather avoid this for now if we can implement direct .did file imports in motoko then this PR and the didc binding generator would get obsolete.