BEX-471 feat(json): emit snake_case twins for every camelCase --json key (transition step)

[piyushsarin-sib]

Summary

Step 1 of moving the CLI's machine-readable output to snake_case: every --json document now carries each camelCase key together with its snake_case twin. Nothing is removed, so every existing jq .appId keeps working. camelCase goes away in the next major (step 2, separate ticket).

Jira: BEX-471 (follow-up to BEX-470). Base branch: features_set-dp-function.

Why

--json output mixed two conventions. Pass-through commands emit the wire's snake_case (app list → app_id, app submit → app_id/form_url, function *); CLI-built objects emit camelCase (create → appId/clientId/redirectUri, upload → upToDate, install/uninstall → accountId, whoami → organizationId, the error envelope → exitCode/statusCode). The smoke suite's own pickId helper accepts three spellings because it cannot predict which one a command uses. app-config.json settled on snake_case in #104; scripts should get one spelling too — but a hard rename is a breaking change the CLI cannot migrate for the user, hence the dual-key transition.

What changed

• src/lib/json-output.ts: withSnakeCaseAliases() runs inside jsonOutput(). For each camelCase key at the top level of the document (per element for an array document) and inside the error envelope, a snake_case twin is inserted right after it. A twin never overwrites a key the object already has.
• Two explicit overrides map to the wire name rather than the mechanical conversion: redirectUri (app create) and redirectUris (app credentials) → redirect_uris.
• Shallow on purpose. Nested objects are not rewritten: ui_app blocks, the upload diff's current/next, Function records and contact data are either already wire-shaped or the user's own data, and rewriting keys inside them would change their meaning.
• No per-command edits. All 36 jsonOutput call sites get the behaviour from the one function.

Examples from the built binary:

$ brevo app delete --app-id … --force --json
{"deleted":true,"appId":"…","app_id":"…"}

$ brevo app list --json        # unauthenticated → envelope
{"error":{"name":"CliError","message":"Not authenticated. Run: brevo login","exitCode":1,"exit_code":1}}

Docs

• agent-context/SKILL.md (Hard rules) and agent-context/AGENTS.md (Conventions): new rule — both spellings are present, prefer snake_case, camelCase is deprecated and removed in the next major. JSON-errors sections and the scaffoldSkipped mention updated to show both keys.
• Changeset: appended to the branch's pending .changeset/function-app-type-registry.md (minor).
• Public docs (CLI reference --json examples, JSON errors section) need the same note; flagged in BEX-471 for product/docs.

Tests

• json-output.test.ts: new withSnakeCaseAliases suite — ordering, no-overwrite, redirect_uris override, multi-hump keys, shallow behaviour, array documents, error envelope, primitives, and that jsonOutput writes the aliased form. emitJsonError expectation updated.
• The seven command tests that pinned an exact camelCase shape (delete, withdraw, install ×2, uninstall ×2) now pin both spellings.
• Smoke scripts untouched: pickId and the created.appName / created.redirectUri assertions keep passing; they switch to snake_case-only in step 2.

Not in this PR (step 2, next major)

Removing the camelCase keys, tightening the smoke helper to snake_case only, and a breaking-change changelog entry.

Checks

• yarn lint ✅
• yarn test:ci ✅ (70 suites, 1600 tests)
• yarn build ✅
• yarn format:check ✅

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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