diff --git a/internal/scaffold/fullsend-repo/skills/retro-analysis/SKILL.md b/internal/scaffold/fullsend-repo/skills/retro-analysis/SKILL.md
index da1f54943a..1632bbf1b5 100644
--- a/internal/scaffold/fullsend-repo/skills/retro-analysis/SKILL.md
+++ b/internal/scaffold/fullsend-repo/skills/retro-analysis/SKILL.md
@@ -123,6 +123,59 @@ Use multiple searches with different keyword combinations if the first returns n
 
 When skipping, note the duplicate in your `summary` field so the human understands what was filtered and why.
 
+### Evidence issue cap
+
+Evidence proposals use the title format `Evidence for #N` (where `N` is
+the parent issue number). This convention is how the retro agent links
+data points back to a systemic issue — always use this exact format
+when filing evidence.
+
+Before filing an evidence proposal, check how many open evidence issues
+already exist for that parent.
+
+Dispatch a subagent to count existing evidence issues:
+
+```bash
+gh api \
+  "search/issues?q=repo:<target_repo>+is:issue+is:open+in:title+%22Evidence+for+%23N%22&per_page=1" \
+  --jq '.total_count'
+```
+
+Replace `<target_repo>` with the proposal's target repository and `N`
+with the parent issue number.
+
+If the count query fails, returns a non-numeric result, or the
+subagent errors out, treat the count as >= 5 (fail closed) and skip
+the evidence proposal. Do not file evidence when the cap cannot be
+verified.
+
+**If the count is >= 5:**
+
+1. **Skip the evidence proposal entirely.** Do not include it in the
+   `proposals` array.
+2. **Note the cap in your summary.** Mention that the pattern is
+   already well-documented with sufficient data points. Include the
+   parent issue number and the current PR/issue as an additional data
+   point so the information is not lost — it just does not warrant a
+   new issue.
+
+Example summary note:
+
+> Pattern for #N is well-documented (≥5 evidence issues). This
+> PR adds another data point but does not warrant a new evidence
+> issue.
+
+**If the count is < 5:** proceed with filing the evidence proposal
+normally.
+
+Only open evidence issues count toward the cap — closed issues do not.
+
+**Concurrency note:** Two retro runs triggered by different PRs can
+both query the count before either files, causing both to see the same
+value and potentially exceeding the cap by one. This is an accepted
+limitation — the cap is advisory and a brief overshoot does not
+meaningfully harm the issue tracker.
+
 ## Localization guidance
 
 When deciding where a proposed change belongs: