feat(signals): add auto-scoring middleware for signal quality assessment (closes bounty #25)

Adds scoreSignal() — a pure TypeScript function that evaluates five quality
dimensions at submission time and stores results with each signal row:

- sourceQuality  (0-30): 1 source=10pts, 2=20pts, 3+=30pts
- thesisClarity  (0-25): headline word-count sweet-spot + body length bonus
- beatRelevance  (0-20): tag overlap with beat slug keywords
- timeliness     (0-15): source URLs containing current/prev year
- disclosure     (0-10): non-empty + tool/model keyword mention bonus

Schema: adds quality_score INTEGER and score_breakdown TEXT (JSON) columns
via MIGRATION_SIGNAL_SCORING_SQL (migration version 12). Both are nullable
so existing rows remain valid without any backfill.

The scorer is pure (no I/O, no DB calls) so it adds zero async overhead
to the POST /signals handler and is fully testable in isolation.

Also adds src/__tests__/signal-scorer.test.ts with 20 unit tests covering
all five dimensions plus edge cases (empty sources, null disclosure, etc).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: tfireubs-ui

src/__tests__/signal-scorer.test.ts

@@ -0,0 +1,244 @@
+import { describe, it, expect } from "vitest";
+import { scoreSignal } from "../lib/signal-scorer";
+
+/**
+ * Unit tests for the signal quality auto-scorer.
+ * All tests are pure — no network, no DB, no cloudflare bindings needed.
+ */
+
+const MINIMAL_SIGNAL = {
+  headline: "Bitcoin price rises",
+  body: null,
+  sources: [],
+  tags: [],
+  beat_slug: "agent-economy",
+  disclosure: null,
+};
+
+describe("scoreSignal — sourceQuality dimension", () => {
+  it("returns 0 pts for zero sources", () => {
+    const result = scoreSignal({ ...MINIMAL_SIGNAL, sources: [] });
+    expect(result.breakdown.sourceQuality).toBe(0);
+  });
+
+  it("returns 10 pts for 1 source", () => {
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      sources: [{ url: "https://example.com/news/2026/article", title: "Example" }],
+    });
+    expect(result.breakdown.sourceQuality).toBe(10);
+  });
+
+  it("returns 20 pts for 2 sources", () => {
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      sources: [
+        { url: "https://example.com/a", title: "A" },
+        { url: "https://example2.com/b", title: "B" },
+      ],
+    });
+    expect(result.breakdown.sourceQuality).toBe(20);
+  });
+
+  it("returns 30 pts for 3+ sources", () => {
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      sources: [
+        { url: "https://a.com", title: "A" },
+        { url: "https://b.com", title: "B" },
+        { url: "https://c.com", title: "C" },
+      ],
+    });
+    expect(result.breakdown.sourceQuality).toBe(30);
+  });
+});
+
+describe("scoreSignal — thesisClarity dimension", () => {
+  it("gives 5 pts for a headline that is too short (< 5 words)", () => {
+    const result = scoreSignal({ ...MINIMAL_SIGNAL, headline: "Bitcoin rises" });
+    expect(result.breakdown.thesisClarity).toBe(5);
+  });
+
+  it("gives 10 pts for headline with 5–7 words", () => {
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      headline: "Bitcoin hits new all-time high today",
+    });
+    expect(result.breakdown.thesisClarity).toBe(10);
+  });
+
+  it("gives 15 pts for headline with 8–15 words", () => {
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      headline: "Bitcoin breaks one hundred thousand dollars driven by institutional ETF demand",
+    });
+    expect(result.breakdown.thesisClarity).toBe(15);
+  });
+
+  it("adds 10 pts bonus when body is longer than 200 chars, capped at 25", () => {
+    const longBody = "A".repeat(201);
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      headline: "Bitcoin breaks one hundred thousand dollars driven by institutional ETF demand",
+      body: longBody,
+    });
+    expect(result.breakdown.thesisClarity).toBe(25);
+  });
+
+  it("does not award body bonus for body <= 200 chars", () => {
+    const shortBody = "Short body.";
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      headline: "Bitcoin breaks one hundred thousand dollars driven by institutional ETF demand",
+      body: shortBody,
+    });
+    expect(result.breakdown.thesisClarity).toBe(15);
+  });
+});
+
+describe("scoreSignal — beatRelevance dimension", () => {
+  it("returns 0 pts when no tags", () => {
+    const result = scoreSignal({ ...MINIMAL_SIGNAL, tags: [], beat_slug: "agent-economy" });
+    expect(result.breakdown.beatRelevance).toBe(0);
+  });
+
+  it("returns 10 pts for 1 tag matching beat keyword", () => {
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      tags: ["agent"],
+      beat_slug: "agent-economy",
+    });
+    expect(result.breakdown.beatRelevance).toBe(10);
+  });
+
+  it("returns 20 pts for 2+ tags matching beat keywords", () => {
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      tags: ["agent", "economy"],
+      beat_slug: "agent-economy",
+    });
+    expect(result.breakdown.beatRelevance).toBe(20);
+  });
+
+  it("returns 0 pts when tags don't overlap with beat keywords", () => {
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      tags: ["ordinals", "runes"],
+      beat_slug: "agent-economy",
+    });
+    expect(result.breakdown.beatRelevance).toBe(0);
+  });
+});
+
+describe("scoreSignal — timeliness dimension", () => {
+  it("returns 0 pts for empty sources", () => {
+    const result = scoreSignal({ ...MINIMAL_SIGNAL, sources: [] });
+    expect(result.breakdown.timeliness).toBe(0);
+  });
+
+  it("returns 15 pts when any source URL contains the current year", () => {
+    const currentYear = new Date().getFullYear();
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      sources: [{ url: `https://news.example.com/${currentYear}/story`, title: "Story" }],
+    });
+    expect(result.breakdown.timeliness).toBe(15);
+  });
+
+  it("returns 15 pts when source URL contains previous year", () => {
+    const prevYear = new Date().getFullYear() - 1;
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      sources: [{ url: `https://news.example.com/${prevYear}/story`, title: "Old Story" }],
+    });
+    expect(result.breakdown.timeliness).toBe(15);
+  });
+
+  it("returns 8 pts when no year match found in source URLs", () => {
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      sources: [{ url: "https://news.example.com/bitcoin-macro-story", title: "Story" }],
+    });
+    expect(result.breakdown.timeliness).toBe(8);
+  });
+});
+
+describe("scoreSignal — disclosure dimension", () => {
+  it("returns 0 pts for empty disclosure", () => {
+    const result = scoreSignal({ ...MINIMAL_SIGNAL, disclosure: "" });
+    expect(result.breakdown.disclosure).toBe(0);
+  });
+
+  it("returns 0 pts for null disclosure", () => {
+    const result = scoreSignal({ ...MINIMAL_SIGNAL, disclosure: null });
+    expect(result.breakdown.disclosure).toBe(0);
+  });
+
+  it("returns 5 pts for non-empty disclosure without tool/model mention", () => {
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      disclosure: "I researched this manually.",
+    });
+    expect(result.breakdown.disclosure).toBe(5);
+  });
+
+  it("returns 10 pts for disclosure mentioning claude", () => {
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      disclosure: "Researched using Claude with aibtc MCP tools.",
+    });
+    expect(result.breakdown.disclosure).toBe(10);
+  });
+
+  it("returns 10 pts for disclosure mentioning LLM", () => {
+    const result = scoreSignal({
+      ...MINIMAL_SIGNAL,
+      disclosure: "LLM-assisted research with manual verification.",
+    });
+    expect(result.breakdown.disclosure).toBe(10);
+  });
+});
+
+describe("scoreSignal — total and shape", () => {
+  it("total equals sum of all breakdown dimensions", () => {
+    const result = scoreSignal({
+      headline: "Agent economy signals new wave of sBTC payment adoption on Stacks network",
+      body: "A".repeat(250),
+      sources: [
+        { url: "https://stacks.org/2026/news", title: "Stacks News" },
+        { url: "https://aibtc.com/2026/updates", title: "AIBTC Updates" },
+        { url: "https://x.com/2026/post", title: "Post" },
+      ],
+      tags: ["agent", "economy", "sbtc"],
+      beat_slug: "agent-economy",
+      disclosure: "Researched using Claude and aibtc MCP skills.",
+    });
+    const { sourceQuality, thesisClarity, beatRelevance, timeliness, disclosure } =
+      result.breakdown;
+    expect(result.total).toBe(
+      sourceQuality + thesisClarity + beatRelevance + timeliness + disclosure
+    );
+  });
+
+  it("returns a score between 0 and 100 inclusive", () => {
+    const result = scoreSignal(MINIMAL_SIGNAL);
+    expect(result.total).toBeGreaterThanOrEqual(0);
+    expect(result.total).toBeLessThanOrEqual(100);
+  });
+
+  it("returns maximum score of 100 for a fully-formed signal", () => {
+    const result = scoreSignal({
+      headline: "Agent economy signals new wave of sBTC payment adoption on Stacks network",
+      body: "A".repeat(250),
+      sources: [
+        { url: "https://stacks.org/2026/news", title: "Stacks News" },
+        { url: "https://aibtc.com/2026/updates", title: "AIBTC Updates" },
+        { url: "https://x.com/2026/post", title: "Post" },
+      ],
+      tags: ["agent", "economy"],
+      beat_slug: "agent-economy",
+      disclosure: "Researched using Claude and aibtc MCP skills.",
+    });
+    expect(result.total).toBe(100);
+  });
+});