WhatsApp Per-OSA Provisioning with WABA-per-Specialist Identity Model

⚠️ Draft — not yet implemented. This subdocument proposes tables and workflows that do not exist in any environment. WhatsApp channel credentials are currently per-Org (integration_credentials). The osa_channel_endpoints table and per-OSA WhatsApp number provisioning proposed here are design proposals only.

Status: Draft (subdocument of ADR-030) Date: 2026-06-03 Issue: #1471 Parent ADRs: ADR-007, ADR-020 (this design extends row 6 of the matrix for WhatsApp) Implementation tracking: dedicated P2 follow-up issue (to be opened post-acceptance)

1. Product invariants

Three rules govern WhatsApp at h.work. They are h.work product decisions, not WhatsApp/Meta platform requirements.

Invariant I-1 — Specialist owns one primary WABA

Every Specialist that engages with WhatsApp owns exactly one primary WhatsApp Business Account (WABA). The WABA is the Specialist's WhatsApp identity container. It isolates:

sender pool
profile lifecycle
WhatsApp quality state and messaging-limit tier
Meta business verification artifact (verified business name, business info)
provisioning / suspension / deprovisioning lifecycle
operational ownership boundary

A Specialist MAY also own zero or more secondary WABAs for region / compliance / migration / brand-quality isolation reasons (see §11). Secondary WABAs do not increase phone-number capacity (which is portfolio-wide; see Invariant I-4) and do not change the identity ownership rule.

Invariant I-2 — Every OSA gets a dedicated phone number

By default, each (Org × Specialist) assignment — an OSA — receives one dedicated WhatsApp phone number, registered under that Specialist's primary (or assigned secondary) WABA. The phone number is the deterministic routing key for that OSA.

Invariant I-3 — Inbound To-number resolves exactly one OSA

Every WhatsApp inbound message resolves to exactly one OSA via single-row lookup on the inbound To number. From the resolved OSA endpoint the platform derives:

org_id
specialist_id
channel_endpoint_id
conversation scope (per ADR-020 row 1)
RLS GUC values (app.current_org_id, app.current_specialist_id)

There is no second-step routing in the default model. A To number that does not resolve to a provisioned endpoint is rejected at the inbound webhook.

Invariant I-4 — Capacity is bounded by Meta's portfolio-wide cap (not by WABA count)

Meta enforces phone-number capacity at the business portfolio level, not per WABA. As of the 2026-06-03 verification of this design:

Account state	Maximum phone numbers (portfolio-wide, across all WABAs)
New / unverified business portfolio	2
Business-verification approved (Meta-side messaging-quality review) OR ≥ 2,000 delivered template messages within a 30-day moving period	20 (auto-raised)
Above 20	Manual Meta Direct Support ticket required (no documented SLA)

In addition, since October 2025, messaging limits also apply at the business portfolio level, not per phone number — phone numbers within a portfolio share the portfolio's daily/30-day messaging quota.

Implication for h.work:

Creating additional WABAs inside the same portfolio does not bypass the cap.
The "one WABA per Specialist" decision (I-1) is an h.work identity-isolation choice; it does not unlock additional capacity.
The platform-wide ceiling on simultaneously-provisioned WhatsApp OSAs equals the portfolio cap. With current state (unverified, cap = 2), the platform can support at most 2 OSAs on WhatsApp regardless of Specialist count.
Reaching cap = 20 requires either passing Meta business verification or a sustained outbound message-volume baseline, both of which are operational pre-requisites for any meaningful WhatsApp rollout.
Beyond 20, every additional number is a manual support ticket — capacity planning must treat OSA growth on WhatsApp as a slow path.

Sources (verified 2026-06-03; revalidate at implementation time):

Twilio Error 63104 — twilio.com/docs/api/errors/63104 — "Meta restricts unverified businesses to 2 phone numbers across all WABAs"
Meta — Business phone numbers — developers.facebook.com/documentation/business-messaging/whatsapp/business-phone-numbers/phone-numbers
Meta — WhatsApp Business Messaging Limits — developers.facebook.com/docs/whatsapp/messaging-limits/
Vonage support — api.support.vonage.com/hc/en-us/articles/13159743458460

2. Display identity model (WABA-level vs sender-level)

WhatsApp surfaces two distinct display names, and the design must be explicit about both.

2.1 WABA verified business name (one per Specialist)

The WABA's Meta-verified business name is the Specialist's platform-level identity.

WABA verified business name  =  "{Specialist.firstName} by h.work"
                                 example: "Kai by h.work"

This name appears in Meta business verification artifacts, is what Meta validates against the legal entity (h.work), and is expensive to change (requires Meta re-verification). It is therefore:

Set at Specialist creation time
Owned by the Specialist (not the Org)
Changed only through a Specialist-rename event with Meta re-verification

It is not parameterized by Org.

2.2 Per-number sender display name (one per OSA)

The sender-level display name surfaces at the per-phone-number business profile and is what most customers see in their WhatsApp contact list when they save the number.

Sender display name  =  "{Org.shortName} {Specialist.domain} by h.work"
                         example: "Acme KYC by h.work"

Set at OSA provisioning time; updated when Org name or Specialist domain attribute changes. Provider-side limits on display name update frequency / review must be respected by the sync job (see §6).

2.3 Profile fields

Field	Source	Per-WABA or per-number
Verified business name	`specialists.firstName` + " by h.work"	per-WABA (Specialist-level)
Display name (sender)	`org.shortName` + " " + `specialists.domain` + " by h.work"	per-number (OSA-level)
Profile photo	`specialists.avatar_url`	per-number, synced from Specialist
About	`specialists.description` (truncated)	per-number
Business category	`specialists.business_category`	per-WABA
Website / address / email	(h.work standard contact info or per-OSA opt-in)	per-number

Identity rule: the Specialist row is the source for firstName, avatar_url, description, domain. Identity-related changes to a Specialist row trigger sync to every provisioned WhatsApp endpoint of that Specialist (rate-limited; see §6).

3. Architecture overview

Meta Business Account / Portfolio: h.work
│
├── WABA-Kai          (Specialist = Kai, Domain = KYC)
│   verified_name = "Kai by h.work"
│   role = primary
│   ├── +1-555-100-0001  →  OSA(Kai, Acme)       sender: "Acme KYC by h.work"
│   ├── +1-555-100-0002  →  OSA(Kai, BigCorp)    sender: "BigCorp KYC by h.work"
│   └── +1-555-100-0003  →  OSA(Kai, DataCorp)   sender: "DataCorp KYC by h.work"
│
├── WABA-Mei          (Specialist = Mei, Domain = Finance)
│   verified_name = "Mei by h.work"
│   role = primary
│   ├── +1-555-200-0001  →  OSA(Mei, Acme)       sender: "Acme Finance by h.work"
│   ├── +1-555-200-0002  →  OSA(Mei, DataCorp)
│   └── +1-555-200-0003  →  OSA(Mei, ShopCo)
│
└── WABA-Lin          (Specialist = Lin, Domain = E-commerce)
    verified_name = "Lin by h.work"
    role = primary
    ├── +1-555-300-0001  →  OSA(Lin, BigCorp)
    └── +1-555-300-0002  →  OSA(Lin, ShopCo)

Cardinality:

Object	Count formula	Bound
WABA (primary)	M = number of Specialists with WhatsApp	one per Specialist
WABA (secondary)	0..K per Specialist	exception-driven
Phone number	sum(OSAs per Specialist with WhatsApp enabled)	one per OSA
Endpoint row	identical to phone number count	one per OSA

4. Inbound routing

Customer (Bob) → WhatsApp → +1-555-100-0002 ("Kai for BigCorp")
   │
   ▼
Twilio BSP webhook → POST /v1/channels/whatsapp/webhook
   body.To   = whatsapp:+15551000002
   body.From = whatsapp:<bob_phone>
   body.Body = <message>
   header X-Twilio-Signature = <hmac>
   │
   ▼
WhatsAppController
   1. Verify HMAC signature
   2. InboundDedupService.check('whatsapp', MessageSid)
   3. Resolve endpoint:
        SELECT *
          FROM osa_channel_endpoints
         WHERE channel_type        = 'whatsapp'
           AND external_id         = 'whatsapp:+15551000002'
           AND provisioning_status = 'provisioned'
           AND revoked_at IS NULL;
   4. Derive (org_id, specialist_id) from endpoint.osa_id
   5. rls.setBoth({ org_id, specialist_id })
   6. Customer.findOrCreate({ org_id, external_id: 'whatsapp:'+from, channel: 'whatsapp' })
   7. Conversation.findOrCreateByChannel(...)
   8. Message saved → agent dispatch → expert queue

Invariant check (enforced in inbound handler unit tests):

expect(endpoint.specialist_id).toBe(conversation.specialist_id);
expect(endpoint.org_id).toBe(conversation.org_id);
// no conversation may be created with specialist_id different from the endpoint's specialist_id

A To number that fails to resolve a provisioned endpoint logs a structured event (whatsapp.inbound.endpoint_not_found) and rejects the webhook with 404. No fallback routing.

5. Outbound dispatch

async dispatch(osaId: string, payload: WhatsAppPayload): Promise<void> {
  const endpoint = await endpoints.findActive({ osaId, channel_type: 'whatsapp' });
  if (!endpoint) throw new ChannelNotProvisionedError('whatsapp', osaId);

  const persona  = await personas.findOne(endpoint.persona_id);
  const identity = await specialists.findOne(osa.specialist_id);
  const creds    = await secretsManager.get(endpoint.credentials_secret_ref);

  await withCircuit('whatsapp', () =>
    withRetry(() =>
      twilio(creds).messages.create({
        from: endpoint.external_id,
        to:   payload.to,
        body: renderBody(payload, identity),
      }),
      { maxAttempts: 3, baseDelayMs: 200, label: 'dispatch.whatsapp' },
    ),
  );
}

Customer's WhatsApp client renders the sender as the per-number sender display name + profile photo + about (all derived from Specialist identity per §2).

6. Identity sync job

@OnEvent('specialist.updated')
async onSpecialistChanged({ specialistId, changedFields }: SpecialistChange) {
  if (!intersects(changedFields, IDENTITY_FIELDS)) return;

  const endpoints = await endpoints.findAll({
    channel_type: 'whatsapp',
    osa: { specialist_id: specialistId },
    provisioning_status: 'provisioned',
    revoked_at: IsNull(),
  });

  for (const ep of endpoints) {
    await channelSyncQueue.add('sync-whatsapp', {
      endpointId: ep.id,
      changedFields,
    }, {
      jobId: `whatsapp-sync-${ep.id}`,          // dedup
      attempts: 5,
      backoff: { type: 'exponential', delay: 60_000 },
    });
  }
}

The sync processor:

Resolves endpoint → persona → identity
Pushes per-field updates to the provider (profile_picture, about, sender display name)
Records per-field result in osa_channel_endpoints.profile_sync_state JSONB
Backs off and DLQs on provider 4xx/5xx
Respects provider-side throttling (e.g., daily profile-update caps); throttle limits live in a provider-config table, not hard-coded

Fields with constraints:

WABA verified business name — not synced automatically; requires Specialist-rename event + Meta re-verification job
WABA business category — not synced automatically
Per-number sender display name — synced, may be subject to provider review
Per-number profile photo / about — synced, rate-limited

7. Data model

-- =========================================================================
-- L2: Specialist's WhatsApp identity container (one primary per Specialist)
-- =========================================================================
CREATE TABLE specialist_channel_personas (
  id                       UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  specialist_id            UUID NOT NULL REFERENCES specialists(id) ON DELETE CASCADE,
  channel_type             VARCHAR(32) NOT NULL,
  provider                 VARCHAR(32) NOT NULL,       -- 'twilio' | 'meta_cloud' (future)
  role                     VARCHAR(16) NOT NULL DEFAULT 'primary',
                                                       -- 'primary' | 'secondary'
  shard_key                VARCHAR(64),                -- 'region:US' | 'compliance:HIPAA' | 'migration:...' | 'quality_isolation' | etc.
                                                       -- NOTE: 'capacity' is NOT a valid shard_key for WhatsApp
                                                       -- because phone-number cap is portfolio-wide (Invariant I-4).
  external_app_id          VARCHAR(255),               -- WABA ID
  verified_business_name   VARCHAR(255),               -- "Kai by h.work"
  business_category        VARCHAR(64),
  verification_status      VARCHAR(32) NOT NULL DEFAULT 'pending',
                                                       -- 'pending' | 'in_review' | 'verified' | 'rejected' | 'suspended'
  provisioning_status      VARCHAR(32) NOT NULL DEFAULT 'pending',
                                                       -- 'pending' | 'provisioning' | 'provisioned' | 'suspended' | 'failed'
  metadata                 JSONB NOT NULL DEFAULT '{}',
  created_at               TIMESTAMPTZ NOT NULL DEFAULT now(),
  updated_at               TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE UNIQUE INDEX uniq_specialist_primary_persona
  ON specialist_channel_personas (specialist_id, channel_type)
  WHERE role = 'primary';

CREATE INDEX idx_persona_specialist ON specialist_channel_personas (specialist_id);
CREATE INDEX idx_persona_status ON specialist_channel_personas (channel_type, provisioning_status);

-- =========================================================================
-- L3: Per-OSA WhatsApp endpoint (one phone number per OSA, default mode)
-- =========================================================================
CREATE TABLE osa_channel_endpoints (
  id                         UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  osa_id                     UUID NOT NULL REFERENCES org_specialist_assignments(id) ON DELETE CASCADE,
  org_id                     UUID NOT NULL,
  specialist_id              UUID NOT NULL,
  channel_type               VARCHAR(32) NOT NULL,
  persona_id                 UUID NOT NULL REFERENCES specialist_channel_personas(id),
  provider                   VARCHAR(32) NOT NULL,    -- mirrors persona.provider
  external_id                VARCHAR(64) NOT NULL,    -- 'whatsapp:+15551000001'
  external_phone_number_id   VARCHAR(64),             -- Meta phone_number_id
  twilio_sender_sid          VARCHAR(64),
  twilio_messaging_service_sid VARCHAR(64),
  sender_display_name        VARCHAR(255),            -- "Acme KYC by h.work"
  credentials_secret_ref     TEXT NOT NULL,           -- Secrets Manager ARN
  webhook_secret_ref         TEXT NOT NULL,
  provisioning_status        VARCHAR(32) NOT NULL DEFAULT 'pending',
                                                       -- 'pending' | 'number_acquired' | 'sender_registered'
                                                       -- | 'profile_configured' | 'webhook_configured'
                                                       -- | 'provisioned' | 'suspended' | 'failed' | 'released'
  profile_sync_state         JSONB NOT NULL DEFAULT '{}',
                                                       -- per-field {status, last_synced_at, last_error}
  provisioned_at             TIMESTAMPTZ,
  suspended_at               TIMESTAMPTZ,
  revoked_at                 TIMESTAMPTZ,
  metadata                   JSONB NOT NULL DEFAULT '{}',
  created_at                 TIMESTAMPTZ NOT NULL DEFAULT now(),
  updated_at                 TIMESTAMPTZ NOT NULL DEFAULT now()
);

-- One active endpoint per OSA per channel
CREATE UNIQUE INDEX uniq_osa_channel_active
  ON osa_channel_endpoints (osa_id, channel_type)
  WHERE revoked_at IS NULL;

-- Inbound reverse-lookup key
CREATE UNIQUE INDEX uniq_endpoint_external_id
  ON osa_channel_endpoints (channel_type, external_id)
  WHERE revoked_at IS NULL;

CREATE INDEX idx_endpoints_persona ON osa_channel_endpoints (persona_id);
CREATE INDEX idx_endpoints_specialist ON osa_channel_endpoints (specialist_id, channel_type);
CREATE INDEX idx_endpoints_provisioning ON osa_channel_endpoints (channel_type, provisioning_status);

-- =========================================================================
-- Pricing rate cards (cost model abstraction)
-- =========================================================================
CREATE TABLE channel_pricing_rate_cards (
  id                UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  provider          VARCHAR(32) NOT NULL,            -- 'twilio' | 'meta_cloud'
  channel_type      VARCHAR(32) NOT NULL,            -- 'whatsapp'
  market_code       VARCHAR(8) NOT NULL,             -- ISO country code or '*' for global
  category          VARCHAR(32),                     -- 'marketing' | 'utility' | 'service' | 'authentication' (WhatsApp-specific)
  unit              VARCHAR(32) NOT NULL,            -- 'per_conversation_24h' | 'per_message' | 'phone_number_monthly'
  amount_cents      INTEGER NOT NULL,
  currency          VARCHAR(3) NOT NULL DEFAULT 'USD',
  effective_from    TIMESTAMPTZ NOT NULL,
  effective_until   TIMESTAMPTZ,
  metadata          JSONB NOT NULL DEFAULT '{}',
  created_at        TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE INDEX idx_rate_cards_lookup
  ON channel_pricing_rate_cards (provider, channel_type, market_code, category, effective_from);

Schema notes

osa_channel_endpoints.external_id is NOT NULL in this model. The previously-considered "fronted endpoint with NULL external_id" is deferred to ADR-028 (see §10).
provisioning_status and profile_sync_state are decoupled — an endpoint can be provisioned while individual profile fields are mid-retry.
All cost queries go through channel_pricing_rate_cards. No hard-coded vendor pricing in code.

8. State machines

8.1 Persona (WABA) lifecycle

created
  │
  ▼
provisioning  ──(Meta business verification submitted)──►  in_review
                                                              │
                                                              ▼
                                                   ┌── verified ──┐
                                                   │              │
                                                   ▼              ▼
                                              provisioned       rejected (terminal until edit)
                                                   │
                                                   ▼
                                                suspended ◄──► provisioned
                                                   │
                                                   ▼
                                                deprecated (no new endpoints; existing keep running until revoked)

8.2 Endpoint (phone number) lifecycle

pending
  │
  ▼
number_capacity_pending  ───────►  number_acquired
  ▲    (waiting for portfolio                │
  │     phone-number cap to free             ▼
  │     up or be raised — see I-4)     sender_registered (BSP/Meta sender approval)
  │                                          │
  │                                          ▼
  └── re-check on portfolio-cap-          profile_configured (display name + photo + about set)
       changed event                         │
                                             ▼
                                       webhook_configured
                                             │
                                             ▼
                                       provisioned ◄──► suspended
                                             │
                                             ▼
                                       released (terminal; number returned to
                                                  provider; row stays for audit
                                                  with revoked_at set)

The number_capacity_pending state (added per Meta-cap reality, see Invariant I-4):

When AM enables WhatsApp for an OSA but the portfolio is at its phone-number cap (registered_numbers >= cap), the endpoint row is created in number_capacity_pending rather than failing. This state:

Surfaces in the AM dashboard as "waiting for WhatsApp number capacity"
Listens for portfolio.capacity.changed events (raised by ops when Meta business verification completes or a manual ticket is granted)
On capacity headroom available, transitions automatically to number_acquired and resumes the normal provisioning path
Is reversible: the AM can cancel an OSA waiting in this state without consuming a number slot

Failure & recovery:

Any pre-provisioned stage failure transitions to failed; recovery is "retry in place" (same row, advance) for transient failures, or "abandon + re-provision" (new row) for permanent (e.g., Meta rejection).
Capacity-related rejection at number_acquired step (Twilio/Meta returns "cap reached" error) → endpoint backs off to number_capacity_pending rather than failed.
profile_sync_state failures do not transition provisioning_status. The endpoint stays provisioned; sync job retries via DLQ.
suspended is reversible. released is terminal.

9. Provisioning flow (default per-OSA mode)

9.1 One-time per Specialist (WABA creation)

Trigger: SuperAdmin creates Specialist + opts in to WhatsApp

1. Create specialist_channel_personas row (provisioning_status = 'pending')
2. POST to Meta (via Twilio or direct) to create WABA
     name = "Kai by h.work"
     business_category = specialists.business_category
3. Submit Meta business verification artifacts
4. Persona transitions: pending → provisioning → in_review (async; days possible)
5. On Meta callback: in_review → verified → provisioned
6. Persona now usable as parent for OSA endpoints

Operational note: until the persona reaches provisioned, no OSA endpoints can be created. AM Setup Wizard surfaces persona state and prevents WhatsApp enablement for OSAs of an unprovisioned Specialist.

9.2 Per-OSA (number provisioning)

Trigger: AM enables WhatsApp for OSA (e.g., Kai-for-Acme)

1. Pre-check: persona.provisioning_status = 'provisioned'
2. Create osa_channel_endpoints row (provisioning_status = 'pending')
3. Number acquisition:
     POST /v2/Accounts/{sid}/IncomingPhoneNumbers
     country = osa.org.preferred_market or default
     → external_id = 'whatsapp:+15551000001'
   → status = 'number_acquired'
4. Sender registration:
     POST /v2/Senders (or current Twilio WhatsApp onboarding flow)
     waba_id = persona.external_app_id
     phone   = endpoint.external_id (digit form)
     display_name = compute_sender_display_name(org, specialist)
   → wait for Meta sender approval (async, hours-days)
   → status = 'sender_registered'
5. Profile configuration:
     Set photo, about per §2
   → status = 'profile_configured'
6. Webhook configuration:
     POST webhook URL with per-endpoint secret (stored in Secrets Manager)
   → status = 'webhook_configured'
7. Final transition: 'provisioned'
8. Emit channel.endpoint.provisioned event

All vendor API calls use the ChannelDispatcherService withCircuit + withRetry path and persist a channel_failures row on terminal failure.

9.3 Revocation

Trigger: OSA termination, customer churn, compliance event

revoked_at = now()
Release number with provider (POST .../IncomingPhoneNumbers/{sid}/release)
Deregister sender from WABA
Mark Secrets Manager secret for deletion (30-day soft delete)
Endpoint row preserved for audit; inbound to released number returns 404

10. Out of scope (deferred to other ADRs)

The following are intentionally not part of this design and are deferred:

Feature	Where	Why deferred
Org-shared front-door mode (one WhatsApp number per Org with internal topic-based routing to multiple Specialists)	ADR-028 (future)	Requires topic classifier design, conflicts with ADR-020 row 1 `specialist_id NOT NULL` invariant. Should be designed once with explicit reassignment audit path.
Topic classifier subsystem	ADR-028	Co-located with front-door design.
Meta Cloud API direct (bypass Twilio BSP)	Future ADR	`provider` column allows the abstraction; switch is a per-Specialist re-provision event.
WhatsApp template message management (HSM / approved templates)	Separate spec	Template lifecycle is independent of endpoint lifecycle.
WhatsApp commerce / catalog / payments	Separate product decision	Not in scope of channel infrastructure.

The current ADR commits only to the default per-OSA dedicated number model. Front-door is acknowledged as a future option, not promised.

11. Secondary WABA exception

A Specialist MAY have additional WABAs beyond the primary. Important: secondary WABAs do NOT increase phone-number capacity, because the cap is enforced at the business portfolio level (see Invariant I-4). The capacity ceiling on WhatsApp is raised via Meta business verification + messaging-quality history, not by adding WABAs. Secondary WABAs are therefore reserved for genuinely-separate-deployment reasons:

Reason	`shard_key` value	Use case
Region	`region:<ISO>`	Regional compliance or data-residency requirement that mandates a WABA in a separate business portfolio (different legal entity / regional Meta entity)
Compliance	`compliance:<framework>`	HIPAA / GDPR / PCI / etc. demands per-customer-segment isolation in a separate portfolio
Migration	`migration:<provider>`	Switching BSP (e.g., Twilio → Meta Cloud direct), with old WABA being phased out via dual-write
Brand-quality isolation	`quality_isolation`	Separating a high-quality-rated WABA from a new/untested one to protect messaging-limit tier from cross-contamination

Notably absent from this list: capacity. Adding a secondary WABA in the same business portfolio does not unlock more phone numbers; it splits the same portfolio-wide pool across more containers. The path to more numbers is at the portfolio level (verification, message-volume baseline, or Meta support ticket per Invariant I-4).

Rules:

Each Specialist has exactly one primary WABA (role='primary'). Enforced by partial unique index in §7.
Secondary WABAs do not change Specialist identity ownership. Verified business name remains "{Specialist.firstName} by h.work" across all WABAs.
Endpoint creation may pick a secondary WABA explicitly during provisioning; the choice is recorded on the endpoint.
If a secondary WABA lives in a separate business portfolio (region / compliance separation), it has an independent phone-number cap and messaging-limit pool — but that requires Meta-side legal-entity separation, which is not a default operational lever.

12. Cost model

All vendor pricing lives in channel_pricing_rate_cards. No constants in code, no fixed assumptions in docs.

Cost dimensions:

Per phone number monthly — Twilio rental fee, varies by market
Per conversation 24h window — Meta WhatsApp Business Platform charge, varies by message category and market (Marketing / Utility / Service / Authentication)
Per platform feature (e.g., embedded signup, dedicated IP) — provider-specific

Portfolio-wide quota constraint (since Meta's October 2025 change):

Two distinct Meta-imposed limits both apply at the business portfolio level:

Registered phone-number cap — see Invariant I-4 (2 default → 20 after verification → manual ticket beyond).
Messaging limit (proactive outbound to unique recipients per 24h) — tier ladder per Meta documentation:

Tier	Unique recipients / 24h	Trigger
Unverified (starting)	250	New business portfolio default
Tier 1	1,000	After Meta business verification
Tier 2	10,000	Quality + volume threshold (≥ 50% of current limit used within 7 days, high quality rating)
Tier 3	100,000	Same trigger logic, further escalation
Tier 4	Unlimited	Sustained high quality + volume

Tier upgrades are evaluated by Meta every 6 hours (post-Oct 2025; previously 24-48h). Throughput on standard accounts is approximately 80 messages-per-second; unlimited-tier accounts can be auto-upgraded to up to 1,000 MPS.

Implications for h.work billing and capacity modeling:

LLM cost rollup is still per OSA (ADR-020 row 5), so per-OSA accounting works fine.
Messaging-quota planning is portfolio-wide, not per OSA. A high-volume OSA can exhaust the portfolio's quota and rate-limit other OSAs even when their own per-conversation cost would be low.
The billing rate-card design must allow modeling a shared portfolio messaging quota alongside per-conversation costs (e.g., a quota_overage_cents rate card row that fires once the portfolio quota is exceeded).
Capacity decisions ("should we add OSA #21 on WhatsApp?") become a portfolio-quality decision, not a per-OSA decision.
Reaching Tier 4 (unlimited) is the only state where per-OSA messaging volume is effectively decoupled — until then, every WhatsApp OSA is competing with siblings for the same daily 24h budget.

Billing aggregation:

LLM costs continue to roll up by osa_id via messages.osa_id (ADR-020 row 5)
Channel costs roll up by endpoint_id and aggregate to osa_id for invoicing
Rate-card lookup at billing-run time, not at message-send time (avoids price drift in historical messages)

13. Provider abstraction

persona.provider and endpoint.provider enumerate the backing provider:

twilio — current default; Twilio acts as BSP between h.work and Meta. All API calls go through Twilio.
meta_cloud — future; direct Meta Cloud API. Skipped today because Twilio's embedded signup flow handles BSP onboarding ergonomically.

Switching providers for an existing Specialist is a re-provision event, not an in-place mutation:

Create new persona row under target provider
Create new endpoints under new persona (dual-write while old endpoints still serve inbound)
Notify customers of number change (Meta allows number reuse only in limited cases)
Cut inbound DNS/webhook traffic
Revoke old endpoints + persona

This is expensive enough that provider migration should be a deliberate Specialist-level decision, not an OSA-level toggle.

14. Security and compliance boundaries

Boundary	Isolation provided by
Kai-Acme vs Kai-BigCorp (same Specialist, different Org)	Different phone number + different endpoint row + different `org_id` + different RLS GUC + different webhook secret + different credentials secret ref
Kai-Acme vs Mei-Acme (same Org, different Specialist)	Different WABA + different phone number + different `specialist_id` + different expert_access path (ADR-007)
Kai-Acme vs Mei-BigCorp (different Org, different Specialist)	Both of the above, composed

Threat model coverage:

Twilio account-level credential compromise → all WhatsApp endpoints affected. Mitigated by Twilio sub-account isolation + Secrets Manager per-endpoint secrets.
Per-endpoint webhook secret compromise → single OSA affected. Rotate that endpoint's secret.
Per-endpoint credentials ref compromise → single OSA affected. Rotate the Secrets Manager secret.
WABA-level Meta compromise (e.g., bad actor takes over the Meta business) → all of one Specialist's endpoints affected. Mitigated by Meta 2FA + h.work-only Business Portfolio admin set.

15. Open questions to verify against current vendor docs

Before implementation, the following facts must be confirmed against current Meta / Twilio / WhatsApp documentation. Treat the design above as architecturally correct but vendor-API details are indicative:

Portfolio-wide phone-number cap — verified 2026-06-03 as 2 (unverified) → 20 (after business verification or 2,000-message volume baseline) → manual Meta support ticket beyond. Reconfirm at implementation time; Meta has changed these thresholds historically.
Meta's October 2025 shift to portfolio-wide messaging limits — confirm the exact mechanism by which a portfolio's quota is consumed and whether/how it can be partitioned across phone numbers (or whether partition is impossible by design).
Current Meta Cloud API version + endpoint shapes for phone_number profile updates.
Twilio current WhatsApp Sender onboarding API surface (Embedded Signup vs Senders API; recently changed).
Profile update rate-limits per WABA / per number / per day.
Display name change review requirements (some changes auto-approve, some require Meta review).
WhatsApp Conversation Category pricing model (currently 4-category model; may evolve).
Sender registration approval SLA (typical and worst-case).
Whether a single Meta Business Portfolio caps the number of WABAs h.work can hold within it.
Whether a portfolio's tier upgrade (e.g., from unverified → verified) is reversible if quality drops, and what the recovery path is.

16. Implementation plan

The work is sized for 4-6 PRs, sequenced as expand-contract:

Phase 1 — Schema (Expand)

New tables: specialist_channel_personas, osa_channel_endpoints, channel_pricing_rate_cards
Indexes + partial unique constraints
FK constraints
Migration applies cleanly to active-active cluster (no DDL on existing tables yet)

Phase 2 — Backfill (read-only)

For each existing Org with WhatsApp integration_credentials row: create a single endpoint attached to the Org's primary OSA, marked shared_with_org=true (legacy marker)
Verify endpoint reverse-lookup matches existing routing in shadow mode
No production traffic switched

Phase 2.5 — Portfolio capacity tracking (NEW; required by Invariant I-4)

Add a small operational table + tracker to make the Meta cap visible and gate provisioning correctly:

CREATE TABLE whatsapp_portfolio_capacity (
  id                          UUID PRIMARY KEY DEFAULT gen_random_uuid(),
  portfolio_external_id       VARCHAR(255) NOT NULL UNIQUE,  -- Meta Business Portfolio ID
  registered_phone_numbers    INTEGER NOT NULL DEFAULT 0,
  cap                         INTEGER NOT NULL DEFAULT 2,    -- 2 / 20 / manually-raised value
  cap_source                  VARCHAR(32) NOT NULL,          -- 'default' | 'business_verified' | 'volume_threshold' | 'manual_ticket'
  business_verification_status VARCHAR(32),                  -- 'unverified' | 'in_review' | 'verified' | 'rejected'
  messaging_tier              VARCHAR(32) NOT NULL DEFAULT 'unverified_250',
                                                             -- 'unverified_250' | 'tier_1_1k' | 'tier_2_10k' | 'tier_3_100k' | 'tier_4_unlimited'
  last_meta_sync_at           TIMESTAMPTZ,
  metadata                    JSONB NOT NULL DEFAULT '{}',
  created_at                  TIMESTAMPTZ NOT NULL DEFAULT now(),
  updated_at                  TIMESTAMPTZ NOT NULL DEFAULT now()
);

The provisioning service:

Reads whatsapp_portfolio_capacity before attempting number_acquired step. If registered_phone_numbers >= cap, the endpoint goes to number_capacity_pending (see §8.2).
Subscribes to a portfolio.capacity.changed event (raised by ops tooling when Meta verification completes, when a Meta-side cap raise is granted, or when an existing number is released).
On event, scans osa_channel_endpoints for rows in number_capacity_pending for that portfolio and resumes them FIFO until cap is hit again.
Surfaces portfolio state in the AM ops dashboard so AMs know capacity headroom before promising customers a Setup Wizard date.

This table is NOT the same as osa_channel_endpoints — it is a small operational mirror of Meta's portfolio-level state, refreshed on a schedule and on relevant webhook events.

Phase 3 — Provisioning service + AM Setup Wizard

WhatsAppProvisioningService with state machine
BullMQ jobs: WABA creation, sender registration polling, profile sync, webhook config
AM Setup Wizard adds "Enable WhatsApp" per non-primary OSA
New customer signup uses per-OSA model; existing customers remain on legacy until migrated

Phase 4 — Dual-write inbound + outbound

Inbound: osa_channel_endpoints.findOne({channel_type, external_id}) is the primary path; legacy lookup is fallback with metric
Outbound: ChannelDispatcher.dispatch reads endpoint + persona + identity
7-day production soak; alert on any legacy fallback hit

Phase 5 — Identity sync

@OnEvent('specialist.updated') listener
Per-channel sync processors for WhatsApp (photo, about, sender display name)
Rate-limited via provider config; DLQ on persistent failure

Phase 6 — Switch read + contract

Remove legacy integration_credentials WhatsApp rows
Remove legacy lookup paths
slack_channel_bindings is unaffected by this WhatsApp work

Phase 7 — Pricing rate card

Seed initial rate cards from current Twilio + Meta pricing
Billing service reads rate cards at invoice-run time

17. ADR decision text (drop-in)

For ADR-030 §Per-channel application / WhatsApp:

For WhatsApp, h.work uses a WABA-per-Specialist and phone-number-per-OSA model.

Every Specialist that engages with WhatsApp owns exactly one primary WhatsApp Business Account. This is an h.work product-level identity and isolation invariant, not a WhatsApp platform requirement. The WABA acts as the Specialist's WhatsApp identity container, isolating sender pool, profile lifecycle, quality state, provisioning lifecycle, and operational ownership.

Every Org × Specialist assignment (OSA) requires one dedicated WhatsApp phone number registered under that Specialist's WABA. The phone number is the deterministic routing key for inbound messages. However, actual provisioning is capacity-gated by Meta's portfolio-wide registered-phone-number cap (Invariant I-4): new Meta Business Portfolios are initially capped at 2 phone numbers; the cap auto-raises to 20 after Meta business verification or sustained messaging-volume baseline; beyond 20 requires manual Meta support tickets. h.work cannot assume immediate per-OSA number provisioning during early rollout.

When the portfolio cap is reached, new WhatsApp OSA endpoints are NOT marked failed. They enter the number_capacity_pending state, surface in the AM dashboard as waiting for capacity, and automatically resume provisioning when Meta-side capacity becomes available (verification completes, manual ticket granted, or an existing number is released).

WhatsApp inbound messages resolve to exactly one OSA via single-row lookup on the inbound To number. The platform derives org_id, specialist_id, channel_endpoint_id, and conversation scope from the resolved endpoint. There is no second-step routing in the default model.

The WABA's verified business name takes the form "{Specialist.firstName} by h.work" and is platform-owned (not parameterized by Org). The per-number sender display name takes the form "{Org.shortName} {Specialist.domain} by h.work" and is set at OSA provisioning time. Identity fields (photo, about, name) are sourced from the Specialist row and synced to provisioned endpoints via an event-driven job.

A Specialist MAY own additional secondary WABAs for region, compliance, migration, or brand-quality-isolation reasons. Secondary WABAs do NOT increase phone-number capacity (which is portfolio-wide; see Invariant I-4) and do not change Specialist identity ownership.

Org-shared front-door mode (one WhatsApp number per Org with internal topic-based routing to multiple Specialists) is deferred to ADR-028 and is not part of the default model. Vendor-API specifics (Twilio Senders API shape, Meta Cloud API version, exact pricing categories) are indicative and must be verified against current provider documentation at implementation time.

18. Recommended implementation issue

Title: [P2][feat] WhatsApp per-OSA provisioning with WABA-per-Specialist identity model Parent: #1471 (ADR-030) Labels: priority:p2 type:feature area:backend Scope checklist:

Verification gates before merge:

All vendor API calls behind withCircuit + withRetry + channel_failures DLQ
Inbound handler rejects unresolved To numbers with 404
Identity sync respects provider rate-limits via config-driven throttle
Specialist rename event triggers Meta re-verification job, does not silently fail
E2E test: provision Kai-for-Acme + Kai-for-BigCorp on same WABA, verify inbound routing isolation
E2E test: revoke Kai-for-Acme, verify Kai-for-BigCorp continues to function

One-line summary

One WABA per Specialist as platform-level identity container; one dedicated phone number per OSA as deterministic routing key; provisioning is capacity-gated by Meta's portfolio-wide phone-number cap (2 default → 20 after verification → manual ticket beyond) and OSAs blocked by the cap park in number_capacity_pending until headroom opens; inbound always resolves single OSA via To number; identity sourced from Specialist row, synced to provisioned endpoints; Org-shared front door explicitly deferred to ADR-028.

1. Product invariants​

Invariant I-1 — Specialist owns one primary WABA​

Invariant I-2 — Every OSA gets a dedicated phone number​

Invariant I-3 — Inbound To-number resolves exactly one OSA​

Invariant I-4 — Capacity is bounded by Meta's portfolio-wide cap (not by WABA count)​

2. Display identity model (WABA-level vs sender-level)​

2.1 WABA verified business name (one per Specialist)​

2.2 Per-number sender display name (one per OSA)​

2.3 Profile fields​

3. Architecture overview​

4. Inbound routing​

5. Outbound dispatch​

6. Identity sync job​

7. Data model​

Schema notes​

8. State machines​

8.1 Persona (WABA) lifecycle​

8.2 Endpoint (phone number) lifecycle​

9. Provisioning flow (default per-OSA mode)​

9.1 One-time per Specialist (WABA creation)​

9.2 Per-OSA (number provisioning)​

9.3 Revocation​

10. Out of scope (deferred to other ADRs)​

11. Secondary WABA exception​

12. Cost model​

13. Provider abstraction​

14. Security and compliance boundaries​

15. Open questions to verify against current vendor docs​

16. Implementation plan​

Phase 1 — Schema (Expand)​

Phase 2 — Backfill (read-only)​

Phase 2.5 — Portfolio capacity tracking (NEW; required by Invariant I-4)​

Phase 3 — Provisioning service + AM Setup Wizard​

Phase 4 — Dual-write inbound + outbound​

Phase 5 — Identity sync​

Phase 6 — Switch read + contract​

Phase 7 — Pricing rate card​

17. ADR decision text (drop-in)​

18. Recommended implementation issue​

One-line summary​