aab80dd30b
Document architecture decision to capture `ActivityExecutionContext` snapshots at execution time. Updated TOC and dependency graph to reference the new ADR.
28 lines
1.6 KiB
Markdown
28 lines
1.6 KiB
Markdown
# 4. Activity Execution Snapshots
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**Date:** 2025-08-04
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**Status:** Accepted
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## Context
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Today the `ActivityExecutionContext` is persisted only at *commit points*.
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If an activity references a workflow variable that changes after it has run—but before the next commit—the value saved is the *later* value, not the one that existed when the activity executed.
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As a result, the Workflow Instance Viewer shows misleading data: users expect to see the variable values *at execution time*, not at commit time.
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## Decision
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Capture a **snapshot** of the `ActivityExecutionContext` immediately when an activity executes.
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The snapshot must include:
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* All workflow variables and their values at that moment.
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* Any other execution-specific metadata required for replay or inspection.
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The snapshot is created by serializing the `ActivityExecutionRecord` to JSON and storing it in the database.
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The persistence layer will be updated to handle this new snapshot field, ensuring it is stored alongside the activity execution record.
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## Consequences
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* The Workflow Instance Viewer will now display the exact state that the activity saw, eliminating confusion during debugging and auditing.
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* Additional storage will be consumed for each snapshot. We accept this overhead in exchange for correctness and developer experience.
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* Existing persistence schemas will require a non-breaking migration to store the snapshot payload.
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* Workflow instances before this change will not have snapshots, but they will still be replayable even if the variable values are not accurate at execution time. |