refactor(core): share the query-group subscriber lookup

[gmazoyer]

Why

The GraphQL query that resolves which nodes subscribe to a query group existed in two identical copies, one in the regeneration impact resolver and one in the computed attribute tasks. Both parsed the response the same way and then mapped it to their own type.

A third consumer is coming on the merge path, for IFC-3002, and importing either existing copy from there would close an import loop through the recompute package.

Ticket: IFC-3016.

What changed

The query and its parsing move into backend/infrahub/core/query_group/subscribers.py, which depends on nothing but the client. Both callers map from a shared reference type.

Pure refactor. No behaviour change, no new configuration, no schema or API change.

How to review

Confirm the two call sites still ask the same question and read the same answer.

How to test

uv run invoke backend.test-unit

Impact & rollout

• Backward compatibility: unchanged behaviour.
• Deployment notes: safe to deploy.

Checklist

• Tests added/updated: none needed, the existing callers' tests cover it
• Changelog entry added: no user-facing change
• External docs updated: not applicable
• Internal .md docs updated: not applicable
• I have reviewed AI generated content

[cubic-dev-ai]

1 issue found and verified against the latest diff

Confidence score: 4/5

• In backend/infrahub/config.py, INFRAHUB_COALESCE_PYTHON_RECOMPUTE_AFTER_MERGE currently has no effect despite its description promising enabled/disabled behavior, which could mislead operators about recomputation; document it as inactive or implement the promised behavior.

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="backend/infrahub/config.py">

<violation number="1" location="backend/infrahub/config.py:226">
P2: Custom agent: **Flag AI Slop and Fabricated Changes**

`INFRAHUB_COALESCE_PYTHON_RECOMPUTE_AFTER_MERGE` currently has no effect, but its description promises enabled and disabled behavior. Mark this setting explicitly inert until the Python coalescing pass consumes it, or wire the setting into that pass.</violation>
</file>

<sub>Shadow auto-approve: would not auto-approve because issues were found.

Re-trigger cubic</sub>

[cubic-dev-ai]

P2: Custom agent: Flag AI Slop and Fabricated Changes

INFRAHUB_COALESCE_PYTHON_RECOMPUTE_AFTER_MERGE currently has no effect, but its description promises enabled and disabled behavior. Mark this setting explicitly inert until the Python coalescing pass consumes it, or wire the setting into that pass.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At backend/infrahub/config.py, line 226:

<comment>`INFRAHUB_COALESCE_PYTHON_RECOMPUTE_AFTER_MERGE` currently has no effect, but its description promises enabled and disabled behavior. Mark this setting explicitly inert until the Python coalescing pass consumes it, or wire the setting into that pass.</comment>

<file context>
@@ -221,6 +221,12 @@ class MainSettings(BaseSettings):
     )
+    coalesce_python_recompute_after_merge: bool = Field(
+        default=True,
+        description="When enabled, Python transform computed attributes are recomputed by the "
+        "coalesced merge and rebase pass; when disabled, they fall back to one recompute per "
+        "changed node.",
</file context>

Suggested change

	description="When enabled, Python transform computed attributes are recomputed by the "
	"coalesced merge and rebase pass; when disabled, they fall back to one recompute per "
	"changed node.",
	description="Reserved for the Python transform recompute pass; currently has no effect until that pass is enabled.",

[gmazoyer]

This is intended. We will make use of it in a follow-up PR.

[codspeed-hq]

Merging this PR will not alter performance

✅ 13 untouched benchmarks

---

_{Comparing gma-20260819-ifc-3016 (14fc969) with develop (00e5b35)}