[simen-strand]

Description

External models inherit the pre_statements, post_statements and on_virtual_update from model_defaults, but they never run them, and they're built without the project's macros. If a default statement calls a project macro and you edit it, the plan tries to render the external models' copies and fails:

ConfigError: Failed to resolve macros for
@tag_query('v2')
Macro 'tag_query' does not exist.
 at '.../external_models.yaml'

This PR stops external models from inheriting those three defaults, the same way they already skip the default gateway. Statements set explicitly on an external model are kept. The docs now say the defaults don't apply to external models.

Upgrade impact

Projects whose model_defaults define statements will see a one-off change on their first plan after upgrading:

• Every external model shows as changed (non-breaking), and the models downstream of it as indirectly changed. No backfill is needed.
• Exception: if SQLMesh can't determine the columns of the external model or of any model downstream of it (e.g. SELECT * from an undeclared source), the default external: full auto-categorization makes the change breaking, and that external model's downstream models are backfilled. A forward-only plan, or external: semi, avoids that.

Projects without default statements are unaffected.

Alternatives considered

• If rendering fails, compare the unrendered statements of external models: fingerprints stay the same, so there's no upgrade impact. But external models keep statements that never run, and the fix relies on catching render errors.
• Pass the project's macros to external models: rendering works. But fingerprints still change, so the upgrade impact is the same, and external models still carry statements that never run.

Test Plan

• New unit test: external models no longer inherit the default statements, explicit ones are kept, and SQL models still inherit them.
• New context test, for pre- and post-statements: plan with @tag_query('v1'), change it to v2, plan again. It fails on main with the error above and passes here.
• Upgrade checked by applying state with main and planning with this branch. The results match the impact described above, and a forward-only plan needs no backfill.

Checklist

• I have run make style and fixed any issues
• I have added tests for my changes (if applicable)
• All existing tests pass (make fast-test)
• My commits are signed off (git commit -s) per the DCO

Summary by CodeRabbit

• Bug Fixes

  • External models no longer inherit project-level default pre-statements, post-statements, or virtual-update statements. Statements specified directly on an external model are preserved; other models continue to receive the defaults.
  • Changes to default statements are reflected when determining whether affected SQL models have been modified.

• Documentation

  • Clarified which models receive project-level statement defaults and how defaults combine with model-specific statements.

[coderabbitai]

No actionable comments were generated in the recent review.

Walkthrough

External models no longer inherit project-level pre_statements, post_statements, or on_virtual_update defaults. Explicitly supplied statements remain. Documentation and tests cover the behavior and model modification tracking.

Changes: External model default statements

Layer / File(s)	Summary
Exclude inherited statement defaults sqlmesh/core/model/definition.py, docs/reference/model_configuration.md, tests/core/test_model.py	External models exclude inherited pre-statements, post-statements, and virtual-update defaults. Tests check that explicit external-model statements remain and SQL models still inherit the defaults.
Cover model modification tracking sqlmesh/migrations/v0103_exclude_default_statements_from_external_models.py, tests/core/test_context.py	The migration module adds no-op schema and row migration functions. Context tests check that changing statement defaults marks the SQL model as directly modified and that the external model has no inherited pre- or post-statements.

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Possibly related PRs

• SQLMesh/sqlmesh#6179: Adds a migration module with the same migration version, 0103, for a separate fingerprint change.

Suggested reviewers: mday-io

Merge Risk: Low · up to 644e0

Projects with default statements may see downstream backfills on their first plan after upgrading. Document that condition and its stated workarounds before merging, or accept the documentation gap as a bounded follow-up.

Security architecture risk: Low · up to 0fe06

The change narrows which models receive project statements without adding execution privileges. The main risk is the first upgraded plan: affected external models can cause downstream rebuilds when column information is incomplete. Migration recovery behavior is unchanged, but interruption and concurrent-upgrade behavior were not fully established.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — The supported propagation scope is affected external models and their downstream dependency graphs in a project. The reviewed change does not add credentials or a new privileged sink; its wider effects arise through existing fingerprinting, planning and migration paths.

Trust Boundaries and Controls

• observed — The routed test functions, including write_config, operate within temporary test fixtures rather than exposing production request handlers. The migration functions accept existing database authority but do not use it in their bodies.

Resilience and Maintainability Implications

• observed — The existing snapshot migrator catches fingerprint-computation exceptions and skips the affected traversal without propagating failure. Migration completion can consequently advance the recorded version without invoking rollback for that exception. This behavior is unchanged against the PR base; no PR-specific increase in its failure exposure was established.

Pre-merge checks: 5

Check name	Status	Explanation
Title check		The title names the main change: external models no longer apply model_defaults statements. It matches the summarized code changes in definition.py, the docs, and the tests. It uses the repository's "…
Description check		The description covers the required template sections. The Description section explains the problem (external models inherit pre_statements, post_statements, and on_virtual_update but never run them, …
Docstring Coverage		Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentat…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Title check

Explanation

The title names the main change: external models no longer apply model_defaults statements. It matches the summarized code changes in definition.py, the docs, and the tests. It uses the repository's "Fix:" prefix and is short and specific.

Full details: Description check

Explanation

The description covers the required template sections. The Description section explains the problem (external models inherit pre_statements, post_statements, and on_virtual_update but never run them, and fail to render project macros) and the fix. The Test Plan section lists the unit test, the context test, and a manual upgrade check. The Checklist section is filled in with all four items checked. The author also adds Upgrade impact and Alternatives considered sections, which go beyond the template but add useful context. The template's HTML comment placeholders are removed, and the content is specific to the change.

Full details: Docstring Coverage

Explanation

Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff with cyclomatic complexity of at least 2. Documentation-only edits and deletions within surviving functions are included; unchanged diff context and fully deleted functions are excluded. Analyzed 3 functions across 4 files.

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Recent review info

Run configuration

• Source mode: Auto
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• Layers: defaults
• Review profile: CHILL
• Plan: Advanced
• Run ID: f1371943-da2d-4f78-af1a-0534bbd94672

Commits

Reviewing files that changed from the base of the PR and between 0fe0645 and 644e06b.

Files selected for processing: 3

• sqlmesh/core/model/definition.py
• tests/core/test_context.py
• tests/core/test_model.py

Files skipped from review as they are similar to previous changes: 3

• sqlmesh/core/model/definition.py
• tests/core/test_context.py
• tests/core/test_model.py

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