Bug: cannot retrieve agent (refugee center) address filled in forms via Person entity

[nadavosa]

Problem

When refugee centers (Agents) fill out their address in forms, the address cannot be reliably retrieved through the Person entity. This is a known deep issue.

Current Data Model

The relevant relationships are:

Agent ──→ Address (optional, ManyToOne)
      ──→ AgentPerson[] ──→ Person
                            └──→ Address (optional, ManyToOne)

Address ──→ Postcode (required)
Postcode.value is validated for Berlin/Potsdam postcodes only
Address.title has a UNIQUE constraint (100 chars)

Suspected Root Causes (need investigation)

1. Two separate address fields — Agent.address vs Person.address

• Agent has its own address field
• Each Person linked to that Agent via AgentPerson also has a separate address field
• When a form saves an address, it may be going to Person.address but the query reads Agent.address (or vice versa), so the address appears missing

2. Postcode validation constraint

• Postcode.value is validated to Berlin/Potsdam postcodes only
• If the agent's address is outside that range (or the postcode record doesn't exist yet), Address creation fails silently or throws
• This means the address save succeeds at the form level but the related Address record was never persisted

3. Address.title UNIQUE constraint

• Address.title has a 100-char UNIQUE constraint
• If two agents share a building/address, the second insert fails with a unique constraint violation

4. Person.address is optional but never populated for agent contacts

• Agents are represented as organizations, not persons
• The form may be filling in Person fields thinking it populates the agent's address, but the Agent.address field is never set

Investigation Checklist

• Trace where the address form data is written in the BE (which service/endpoint)
• Confirm whether the FE form POSTs to Person or Agent endpoints
• Check if Postcode validation rejects any agent postcodes
• Check if Address.title uniqueness is causing silent failures
• Determine which path the FE uses to READ the agent address back (Agent.address or Person.address)
• Check if AgentPerson join has a role that should determine which Person's address is "the agent's address"

Expected Behavior

When a refugee center fills in their address through the form, that address should be:

1. Saved correctly (no silent failures from postcode validation or uniqueness constraints)
2. Retrievable via the agent entity in API responses

Notes

• This is a deep structural issue — do not change the schema before the investigation is complete
• Related: the Agent.representative computed getter finds the VOLUNTEER_COORDINATOR AgentPerson, which may be the intended contact whose address should surface