ref(crons): Reorganize incident creation / issue occurrence logic

[ShashankFC]

Test 8

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Replicated from ai-code-review-evaluation/sentry-greptile#8

[greptile-apps]

Greptile Summary

This PR refactors the monitor incident and occurrence creation logic by extracting code from mark_failed.py into two new specialized modules for better separation of concerns.

Key Changes:

• Extracted incident threshold logic into incidents.py (mark_failed_threshold → try_incident_threshold)
• Extracted occurrence creation logic into incident_occurrence.py (create_issue_platform_occurrence → create_incident_occurrence)
• Moved SimpleCheckIn TypedDict to centralized types.py module
• Simplified mark_failed.py to delegate to the new modules

Issues Found:

• Minor typo in docstring: "humam readible" should be "human readable"

Confidence Score: 5/5

• This PR is safe to merge with minimal risk
• Clean refactoring that extracts code into logical modules without changing behavior. The logic is moved verbatim from mark_failed.py into two new files with only function names changed (mark_failed_threshold → try_incident_threshold, create_issue_platform_occurrence → create_incident_occurrence). The SimpleCheckIn type is appropriately moved to the centralized types module. Only issue is a minor typo in a docstring.
• No files require special attention

Important Files Changed

Filename	Overview
src/sentry/monitors/logic/incident_occurrence.py	New file extracting occurrence creation logic from mark_failed.py; includes typo in docstring
src/sentry/monitors/logic/incidents.py	New file extracting incident threshold logic from mark_failed.py; clean refactor with no issues
src/sentry/monitors/logic/mark_failed.py	Simplified by removing extracted logic and delegating to new incidents module
src/sentry/monitors/types.py	Moved SimpleCheckIn TypedDict from mark_failed.py to centralized types module

Sequence Diagram

sequenceDiagram
    participant Consumer as Monitor Consumer
    participant MF as mark_failed.py
    participant TIT as try_incident_threshold<br/>(incidents.py)
    participant CIO as create_incident_occurrence<br/>(incident_occurrence.py)
    participant DB as Database
    participant Kafka as Kafka

    Consumer->>MF: mark_failed(failed_checkin, ts, received)
    MF->>MF: Get failure_issue_threshold from config
    MF->>MF: Calculate next check-in times
    MF->>DB: Update MonitorEnvironment timestamps
    alt Update successful
        MF->>TIT: try_incident_threshold(failed_checkin, threshold, received)
        TIT->>TIT: Check monitor_env.status
        alt Status is OK/ACTIVE
            TIT->>DB: Query previous check-ins
            TIT->>TIT: Check if threshold reached
            alt Threshold reached
                TIT->>DB: Set status to ERROR
                TIT->>DB: Create/get MonitorIncident
            end
        else Status is ERROR
            TIT->>DB: Get active_incident
        end
        alt Incident exists and not muted
            TIT->>DB: Query MonitorCheckIn objects
            loop For each check-in
                TIT->>CIO: create_incident_occurrence(checkins, checkin, incident, received)
                CIO->>CIO: Build IssueOccurrence with evidence
                CIO->>CIO: Build event_data with context
                CIO->>Kafka: produce_occurrence_to_kafka()
            end
        end
        TIT->>TIT: Send monitor_environment_failed signal
        TIT-->>MF: Return True
    else Update failed
        MF-->>Consumer: Return False
    end
    MF-->>Consumer: Return result

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[greptile-apps]

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[greptile-apps]

syntax: Typo: "humam readible" should be "human readable"

Suggested change

	Builds a humam readible string from a list of failed check-ins.
	Builds a human readable string from a list of failed check-ins.

Prompt To Fix With AI

This is a comment left during a code review.
Path: src/sentry/monitors/logic/incident_occurrence.py
Line: 132:132

Comment:
**syntax:** Typo: "humam readible" should be "human readable"

```suggestion
    Builds a human readable string from a list of failed check-ins.
```

How can I resolve this? If you propose a fix, please make it concise.