test(mcp): prove tracedecay_source_edit_reconcile behavior

[ScriptedAlchemy]

Summary

• Prove tracedecay_source_edit_reconcile through the production MCP dispatch, not a schema pin or unit-level journal fixture.
• Assert the tool refuses an uninspected or unretained effect, confirms a rolled-back preimage, and confirms committed bytes only when the live file matches the exact preview.
• Exact retries replay the reconciliation receipt and do not rewrite the file.

Motivation

The MCP suite covered source-edit apply and retry, but never called tracedecay_source_edit_reconcile. Agents that see EffectUnknown have to conclude the retained effect from the live candidate file. This test is that journey.

Changes

• crates/tracedecay/tests/mcp_suite/mcp_handler_test/source_edit_reconcile_test.rs drives the real tool. Publication is interrupted by making the candidate directory unwritable after the journal is durable, which is the production EffectUnknown boundary. Assertions are the returned messages, receipt fields, and the literal file bytes.

Test plan

• cargo test -p tracedecay --features test-transport --test mcp_suite -- source_edit_reconcile reports a non-zero count
• No production code change; clippy is limited to the new test module
• Not a workspace-wide nextest run; this change is one MCP behavior test

Checklist

• CHANGELOG.md not updated: test-only, no user-facing contract change
• No secrets, credentials, or .env files included
• Breaking changes documented (if any): none

  

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[ScriptedAlchemy]

Closing as superseded. A sibling change proving the same tool landed first as #1648.

Evidence from the triage: git log origin/master --diff-filter=A -- mcp_handler_test/source_edit_reconcile_test.rs => f241ad3, carried by b33e5a1 'merge: PR #1648 test(mcp): prove tracedecay_source_edit_reconcile behavior'; same path added in both, 8 conflict hunks

Reopen if the landed version misses an assertion this branch carries; name it and it can be ported as a small follow-up.