fix: let read-only consumers build the provider registry without writing

[lewisjared]

Summary

ProviderRegistry.build_from_config unconditionally upserts provider and diagnostic rows via _register_provider, which is the only step in that method that writes to the database. That makes it impossible for a read-only consumer — notably the ref-app API serving a database mounted read-only — to build the registry: startup crashes with attempt to write a readonly database even though the rows it needs are already registered by ref providers setup and the workers.

This adds a register argument to build_from_config (default True, so every existing caller is unchanged). Read-only consumers pass register=False to hydrate the registry from imported providers without touching the database.

Changes

• ProviderRegistry.build_from_config gains register: bool = True; the _register_provider write loop is skipped when it is False.
• Unit test for the register=False path, plus a TestProviderRegistryReadOnly integration test that migrates and registers a real database, reopens it read-only, and asserts that register=False builds with no write while register=True raises OperationalError (the exact crash this fixes).

Context

This is the climate-ref half of the fix for Climate-REF/ref-app#31; the ref-app API is updated separately to pass register=False on its read-only path.

Summary by CodeRabbit

• New Features

  • You can now build the provider registry without writing to the database, which supports read-only environments.
  • The registry still loads provider configuration and works in memory as before.

• Bug Fixes

  • Improved handling for read-only databases by avoiding write transactions when registration is disabled.
  • Added coverage to confirm database writes fail as expected in read-only mode when registration is enabled.

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Review details

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 58883631-6899-4469-b22c-471e7c5da26f

📥 Commits

Reviewing files that changed from the base of the PR and between 3628226 and cd9e80d.

📒 Files selected for processing (3)

• changelog/791.improvement.md
• packages/climate-ref/src/climate_ref/provider_registry.py
• packages/climate-ref/tests/unit/test_provider_registry.py

📝 Walkthrough

Walkthrough

Adds a register: bool = True parameter to ProviderRegistry.build_from_config, gating the database write transaction so read-only consumers can build the registry without writing to the database. Includes new unit tests for read-only database scenarios and a changelog entry.

Changes

Read-only registry build support

Layer / File(s)	Summary
Add register flag to build_from_config packages/climate-ref/src/climate_ref/provider_registry.py	Adds a register: bool = True parameter, updates the docstring, and wraps the db.session.begin() upsert logic in an if register: conditional so registration only writes to the database when enabled.
Tests validating register flag and read-only DB behaviour packages/climate-ref/tests/unit/test_provider_registry.py	Adds test_create_no_register, a TestProviderRegistryReadOnly suite with a _read_only_db helper, and tests confirming no transaction starts when register=False and that register=True against a read-only DB raises OperationalError.
Changelog entry changelog/791.improvement.md	Documents the new register argument and its use for read-only consumers.

Sequence Diagram(s)

sequenceDiagram
  participant Caller
  participant ProviderRegistry
  participant Database

  Caller->>ProviderRegistry: build_from_config(config, db, register=False)
  ProviderRegistry->>ProviderRegistry: import/configure providers
  alt register is True
    ProviderRegistry->>Database: db.session.begin()
    ProviderRegistry->>Database: upsert provider/diagnostic rows
  else register is False
    ProviderRegistry-->>Caller: skip database write
  end
  ProviderRegistry-->>Caller: return ProviderRegistry instance

Loading

Possibly related issues

• REF_READ_ONLY_DATABASE: provider.configure() still writes to the DB at startup ref-app#31: Addresses the same objective of adding a read-only path for ProviderRegistry.build_from_config to avoid writing diagnostics at startup.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main change: allowing read-only consumers to build the provider registry without database writes.
Description check	✅ Passed	It covers the problem, solution, tests, and context, and mentions the changelog and doc updates.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/read-only-provider-registry

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Flag	Coverage Δ
core	92.44% <100.00%> (+<0.01%)	⬆️
providers	86.97% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...s/climate-ref/src/climate_ref/provider_registry.py	100.00% <100.00%> (ø)

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[lewisjared]

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