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+---
+pr_number: 5772
+title: "feat(B-0914.6): proximity-agent substrate-engineering substrate de-duplication (canonical-form + Jaccard clustering); 19 tests pass"
+author: "AceHack"
+state: "MERGED"
+created_at: "2026-05-28T11:26:37Z"
+merged_at: "2026-05-28T12:16:24Z"
+closed_at: "2026-05-28T12:16:24Z"
+head_ref: "otto-cli/b-0914-6-proximity-agent-substrate-engineering-substrate-deduplication-canonical-form-normalization-2026-05-28"
+base_ref: "main"
+archived_at: "2026-05-28T12:18:27Z"
+archive_tool: "tools/pr-preservation/archive-pr.ts"
+---
+
+# PR #5772: feat(B-0914.6): proximity-agent substrate-engineering substrate de-duplication (canonical-form + Jaccard clustering); 19 tests pass
+
+## PR description
+
+## Summary
+
+Google co-scientist proximity agent pattern generalized to TS-side substrate. Two de-dup mechanisms: canonical-form normalization (deterministic) + Jaccard-similarity clustering (lightweight; no embedding model).
+
+**19 tests pass / 0 fail.**
+
+## Composes with
+
+- B-0914.5 PR #5767 evolution (de-dup Survivor list before mash)
+- B-0914.2 PR #5769 closed-loop (de-dup pre-CI-dispatch)
+- verify-existing-substrate-before-authoring (proximity IS substrate-inventory at runtime scope)
+- additive-not-zero-sum + monad-propagation + asymmetric-authorship
+
+🤖 Generated with [Claude Code](https://claude.com/claude-code)
+
+## Reviews
+
+### COMMENTED — @copilot-pull-request-reviewer (2026-05-28T11:30:46Z)
+
+## Pull request overview
+
+Adds a TypeScript proximity de-duplication substrate for workflow-engine experiments, supporting deterministic canonical-form clustering and lightweight Jaccard/token similarity clustering for near-duplicate hypotheses before ranking/evolution/CI dispatch.
+
+**Changes:**
+- Adds `proximity.ts` with Result-shaped clustering APIs, tokenization, Jaccard similarity, and representative extraction.
+- Adds `proximity.test.ts` with 19 Bun tests covering canonical clustering, similarity clustering, tokenizer behavior, errors, and evolution-substrate composition.
+
+### Reviewed changes
+
+Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.
+
+| File | Description |
+| ---- | ----------- |
+| `tools/workflow-engine/proximity.ts` | Implements proximity de-duplication primitives and public API types. |
+| `tools/workflow-engine/proximity.test.ts` | Adds invariant and behavior coverage for the new proximity substrate. |
+
+## Review threads
+
+### Thread 1: tools/workflow-engine/proximity.ts:23 (resolved)
+
+**@copilot-pull-request-reviewer** (2026-05-28T11:30:45Z):
+
+P1 xref: this docblock references a “B-0914.6 backlog row”, but `docs/backlog/` has no `B-0914.6` row in this checkout. Either add the row in this PR or remove/adjust this cross-reference so the new substrate does not point readers at a non-existent backlog artifact.
+
+### Thread 2: tools/workflow-engine/proximity.ts:63 (resolved)
+
+**@copilot-pull-request-reviewer** (2026-05-28T11:30:46Z):
+
+`Cluster` is returned by both canonical and similarity clustering, but this field is documented as the canonical-form key even though `clusterBySimilarity` fills it with a synthesized similarity label derived from representative tokens. Rename/generalize the field or adjust the contract so callers do not treat similarity results as canonical-form keys.
+
+## General comments
+
+### @chatgpt-codex-connector (2026-05-28T11:26:41Z)
+
+You have reached your Codex usage limits for code reviews. You can see your limits in the [Codex usage dashboard](https://chatgpt.com/codex/cloud/settings/usage).