sdd: signal conceptual Session dialogue synthesized a design for a 7th signal kind — ...

Author: hlubek

.sdd/graph/2026/05/05-215805-s-cpt-8h8.md

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+---
+type: signal
+layer: conceptual
+kind: insight
+refs:
+    - 20260410-110420-s-cpt-s43
+    - 20260504-100323-s-cpt-8tu
+    - 20260423-203503-d-cpt-ygn
+participants:
+    - Christopher
+    - Claude
+confidence: medium
+preflight: skipped
+summary: Session dialogue designed a 7th structural signal kind excluded from catch-up narratives and a two-level topic assignment system combining inline labels at capture with post-capture annotation signals, enabling mechanical lightweight catch-up without synthesis. This addresses the topic-clustering gap (s-cpt-s43) and the roadmap-visibility problem (s-cpt-8tu) while building on the type-system expansion (d-cpt-ygn), whose supersession is required to realize the design.
+summary_hash: 5b0193217e2039edbbdf2839fa524db7
+---
+
+Session dialogue synthesized a design for a 7th signal kind — purely structural, excluded from catch-up narrative, carrying typed edge bundles in frontmatter — and a companion two-level topic assignment system: inline topic labels on entries as the zero-ceremony primary path at capture time, with structural annotation signals for post-capture correction and bulk reorganization. Together these would enable mechanical lightweight catch-up without agent synthesis. The design is exploratory; realising it requires a conceptual decision superseding d-cpt-ygn. See [design dialogue](./05-215805-s-cpt-8h8/annotation-signal-design.md).

.sdd/graph/2026/05/05-215805-s-cpt-8h8/annotation-signal-design.md

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+# `kind: annotation` signal + topic system — design synthesis
+
+## The gap
+
+The existing 6 signal kinds (gap, fact, question, insight, done, actor) represent things noticed about the world or the project. None represents a structural annotation about the graph itself — grouping entries into topics, assigning labels, recording cross-cutting relationships.
+
+Using `kind: insight` for topic clustering was considered but rejected: insights appear in the catch-up narrative as actionable items. Structural annotations should be invisible to the catch-up — present only for querying and rendering.
+
+## Proposed: `kind: annotation`
+
+A 7th signal kind — purely mechanical, excluded from catch-up narrative items. Never appears as a numbered item in the catch-up. Queryable for clustering, ranking, and rendering.
+
+### Frontmatter: typed edge bundles
+
+Each annotation carries a bundle of typed edges. Each edge has its own type and payload; multiple edge types can coexist in one bundle:
+
+```yaml
+edges:
+  - type: topic
+    label: "catch-up/performance"
+    members: [20260504-100323-s-cpt-8tu, 20260505-153647-d-tac-kv5, 20260505-153654-d-tac-qom]
+  - type: topic
+    label: "CLI/UX"
+    members: [20260428-125737-d-tac-kud, 20260505-163757-d-tac-07q, 20260505-162047-d-tac-y9q]
+```
+
+Current known edge type: `topic`. Future types (e.g. `priority`, `external-reference`) can be added without schema changes. The body carries narrative: why this grouping was made, what the topic means, what session produced it.
+
+## Two-level topic assignment
+
+**Primary path (capture time):** Entries carry an inline `topics:` field in frontmatter, assigned at creation. The agent suggests matching labels from existing annotations in the graph. No extra entry needed — zero ceremony for the common case.
+
+```yaml
+topics: ["catch-up/performance", "CLI/UX"]
+```
+
+**Secondary path (post-capture):** Annotation signals handle entries that predate the topic system, bulk reorganizations, and corrections. One annotation signal can assign topics across many entries at once.
+
+The in-memory model builds the topic index as a union of both sources.
+
+## Hierarchical topics via path labels
+
+Labels follow a path convention: `"UX/CLI"` implies membership in `"UX"` by prefix. The renderer does a prefix match — no extra entries needed for parent topics. Inspired by s-cpt-s43's Zettelkasten hierarchical tags proposal.
+
+## Label stability
+
+Topic labels are stable identifiers, not display names — same principle as canonical participant names. Once used, a label is permanent. To restructure: add new annotation signals with correct labels, supersede old ones. Active cluster membership migrates forward; historical entries retain old labels. This avoids the "rename all backlinks" mess of tools like Logseq.
+
+## Edge mutation: additive union model
+
+- **Adding members**: new annotation signal with same label — no supersession needed
+- **Removing members**: supersede the specific annotation signal that added them
+
+Topic membership = union of all non-superseded annotation signals sharing that label + inline `topics:` fields on entries. No negative edges needed; no ordering dependencies.
+
+## Connection to lightweight catch-up
+
+With annotation signals providing pre-computed topic clusters and in-degree + heat-decay providing ranking (s-cpt-rwd), the lightweight catch-up can select and present top-N entries under topic headers using verbatim summaries — no synthesis required.
+
+## Type system impact
+
+Extends signal kinds from 6 to 7, touching the type system contract (d-cpt-ygn). Requires a conceptual decision before implementation. Companion to the `kind: focus` decision proposal (s-cpt-ke6).