syncro: capture Phase-1 live-test findings (email-delivery trap + response shapes)

Test campaign on Howard Test sandbox (customer 36118743) surfaced traps the skill must not
re-learn:
- invoice/estimate email endpoints return 200 "Email sent" even with NO recipient
  (customer.email null) -> never report delivery from the 200; verify customer.email first.
- customer.email is UNIQUE tenant-wide; PUT /customers failure returns
  {success:false,message:[...]} not {customer:{...}} -> check .success.
- POST/PUT /contacts return a FLAT object (.id), not {contact:{...}}; contact recipient
  flags (primary/receives_invoices) are ignored via API.
- POST /contracts write succeeds but body doesn't echo the object; /contracts?customer_id
  doesn't filter server-side -> GET-verify + client-filter.

New living log .claude/standards/syncro/test-findings.md; critical items folded into
syncro.md Hard Rules + Verified Response Shapes. Correction logged to errorlog.md.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

errorlog.md

@@ -19,6 +19,8 @@ Categories (the `[type]` tag): _(none)_ = skill/command execution failure ·
 
 <!-- Append entries below this line -->
 
+2026-07-10 | Howard-Home | syncro/email | [correction] assumed HTTP 200 {message:Email sent} meant the invoice/estimate actually reached the customer; correct is Syncro returns 200 even when customer.email is null (no recipient) - must verify a valid, UNIQUE customer.email before claiming delivery [ctx: customer=36118743 endpoints=POST_/invoices/{id}/email,/estimates/{id}/email]
+
 2026-07-10 | Howard-Home | syncro/assets | [correction] assumed asset writes (POST/PUT create-update), policy_folder_id move, patches, and installed_applications were not doable via the public API; correct is the endpoints exist per the live OpenAPI spec and the prior 'policy_folder_id silently ignored' was a token missing the 'Assets - Policy Change' scope, not an API limitation [ctx: ref=reference-syncro-rmm-api-gui-only endpoint=PUT_/customer_assets/{id}]
 
 2026-07-10 | GURU-BEAST-ROG | guruscan | detached full-chain wrapper died mid-RKill on TPM-PC (marker never written, task->Ready, rkill.log completed fine as orphan) — RKill's process sweep almost certainly killed its own hidden SYSTEM powershell parent; relaunched with -SkipScanners RKill [ctx: host=TPM-PC client=mineralogical-record chain-design-issue]