| name | assessing-impact |
| description | Use when estimating blast radius, finding what depends on a symbol or file, choosing or running affected tests, or verifying a change without a full suite. Trigger before guessing tests or running "cargo test" broadly. Do NOT use to review a diff (tracedecay:reviewing-changes). |
Assessing impact
NO GUESSED TEST LISTS AND NO FULL-SUITE-BY-DEFAULT.
Compute the dependent set and the affected tests from the graph first.
Announce: "Using tracedecay:assessing-impact for ."
Blast radius
- Have changed file paths already? →
tracedecay_diff_context (files):
modified symbols + dependents + affected tests in ONE offline call — prefer
this over separate lookups. Works with no network and no PR.
- Single symbol → resolve to node ID (
tracedecay:exploring-code ladder),
then tracedecay_impact (node_id, shallow max_depth first).
- File-level fan-in →
tracedecay_file_dependents.
- Optional fragility check →
tracedecay_coupling / tracedecay_dependency_depth.
Coverage intelligence (read-only)
| Question | Call |
|---|
| Which tests reach this symbol/file | tracedecay_test_map (empty result = no indexed path, strong-not-absolute evidence of untested) |
| Which tests can see these changed files | tracedecay_affected (files) |
| Where the next test is most needed | tracedecay_test_risk (path?, limit?) |
| "What breaks if I change/touch this" | tracedecay_impact (node_id) for a symbol, tracedecay_affected (files) for changed files |
Running the impacted tests
tracedecay_run_affected_tests (changed_paths, max_tests, profile,
timeout_secs): pass/fail per test with covered source nodes. Cargo/Rust
only — for other stacks use tracedecay_affected to get the test set,
then the project's own runner on exactly that set.- Compile/type failures during the run →
tracedecay:fixing-build-and-type-errors.
Rules
- Everything except
run_affected_tests/diagnostics is read-only — preview
scope freely before running toolchains; respect host approval/run-mode and
avoid duplicate toolchain runs (first diagnostics build can take minutes).
- Coverage is structural: integration tests reaching code through binaries,
fixtures, or IO can be missed. Say so when asserting "untested".
- Refactor checklist wanted →
tracedecay:editing-safely. Whole-diff review →
tracedecay:reviewing-changes.
If tools are deferred or MCP fails
- Deferred: one ToolSearch call —
select:tracedecay_diff_context,tracedecay_impact,tracedecay_affected,tracedecay_test_map,tracedecay_run_affected_tests.
- MCP error:
tracedecay tool diff_context --files … etc. (see
tracedecay:using-the-cli). Do not degrade to running the full suite.
Deliverable
Do not end without all three: (a) impacted symbols + files, (b) the concrete
test set (or pass/fail summary mapped back to source), (c) coverage gaps or
hub risk worth flagging. If the graph cannot see part of the change (e.g.
generated code), state that explicitly instead of widening to a full suite.
Report any tracedecay_metrics: line.
