feat: design taste engine with persistent schema

Adds a cross-session taste profile that learns from design-shotgun
approval/rejection decisions. Biases future design-consultation and
design-shotgun proposals toward the user's demonstrated preferences.

Codex review caught that the plan had "taste engine" as a vague goal
without schema, decay, migration, or placeholder insertion points. This
commit ships the full spec.

Schema v1 at ~/.gstack/projects/$SLUG/taste-profile.json:
- version, updated_at
- dimensions: fonts, colors, layouts, aesthetics — each with approved[]
  and rejected[] preference lists
- sessions: last 50 (FIFO truncation), each with ts/action/variant/reason
- Preference: { value, confidence, approved_count, rejected_count, last_seen }
- Confidence: Laplace-smoothed approved/(total+1)
- Decay: 5% per week of inactivity, computed at read time (not write)

Changes:
- bin/gstack-taste-update: new CLI. Subcommands approved/rejected/show/
  migrate. Parses reason string for dimension signals (e.g.,
  "fonts: Geist; colors: slate; aesthetics: minimal"). Emits taste-drift
  NOTE when a new signal contradicts a strong opposing signal. Legacy
  approved.json aggregates migrate to v1 on next write.
- scripts/resolvers/design.ts: new generateTasteProfile() resolver.
  Produces the prose that skills see: how to read the profile, how to
  factor into proposals, conflict handling, schema migration.
- scripts/resolvers/index.ts: register TASTE_PROFILE and a BIN_DIR
  resolver (returns ctx.paths.binDir, used by templates that shell out
  to gstack-* binaries).
- design-consultation/SKILL.md.tmpl: insert {{TASTE_PROFILE}} placeholder
  in Phase 1 right after the memorable-thing forcing question so the
  Phase 3 proposal can factor in learned preferences.
- design-shotgun/SKILL.md.tmpl: taste memory section now reads
  taste-profile.json via {{TASTE_PROFILE}}, falls back to per-session
  approved.json (legacy). Approval flow documented to call
  gstack-taste-update after user picks/rejects a variant.

Known gap: v1 extracts dimension signals from a reason string passed
by the caller ("fonts: X; colors: Y"). Future v2 can read EXIF or an
accompanying manifest written by design-shotgun alongside each variant
for automatic dimension extraction without needing the reason argument.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/resolvers/design.ts

@@ -948,3 +948,45 @@ echo '{"approved_variant":"<V>","feedback":"<FB>","date":"'$(date -u +%Y-%m-%dT%
 \`\`\``;
 }
 
+export function generateTasteProfile(ctx: TemplateContext): string {
+  return `Read the persistent taste profile if it exists:
+
+\`\`\`bash
+_TASTE_PROFILE=~/.gstack/projects/$SLUG/taste-profile.json
+if [ -f "$_TASTE_PROFILE" ]; then
+  # Schema v1: { dimensions: { fonts, colors, layouts, aesthetics }, sessions: [] }
+  # Each dimension has approved[] and rejected[] entries with
+  # { value, confidence, approved_count, rejected_count, last_seen }
+  # Confidence decays 5% per week of inactivity — computed at read time.
+  cat "$_TASTE_PROFILE" 2>/dev/null | head -200
+  echo "TASTE_PROFILE_FOUND"
+else
+  echo "NO_TASTE_PROFILE"
+fi
+\`\`\`
+
+**If TASTE_PROFILE_FOUND:** Summarize the strongest signals (top 3 approved entries
+per dimension by confidence * approved_count). Include them in the design brief:
+
+"Based on ${'\\${SESSION_COUNT}'} prior sessions, this user's taste leans toward:
+fonts [top-3], colors [top-3], layouts [top-3], aesthetics [top-3]. Bias
+generation toward these unless the user explicitly requests a different direction.
+Also avoid their strong rejections: [top-3 rejected per dimension]."
+
+**If NO_TASTE_PROFILE:** Fall through to per-session approved.json files (legacy).
+
+**Conflict handling:** If the current user request contradicts a strong persistent
+signal (e.g., "make it playful" when taste profile strongly prefers minimal), flag
+it: "Note: your taste profile strongly prefers minimal. You're asking for playful
+this time — I'll proceed, but want me to update the taste profile, or treat this
+as a one-off?"
+
+**Decay:** Confidence scores decay 5% per week. A font approved 6 months ago with
+10 approvals has less weight than one approved last week. The decay calculation
+happens at read time, not write time, so the file only grows on change.
+
+**Schema migration:** If the file has no \`version\` field or \`version: 0\`, it's
+the legacy approved.json aggregate — \`${ctx.paths.binDir}/gstack-taste-update\`
+will migrate it to schema v1 on the next write.`;
+}
+

scripts/resolvers/index.ts

@@ -9,7 +9,7 @@ import type { TemplateContext, ResolverFn } from './types';
 import { generatePreamble } from './preamble';
 import { generateTestFailureTriage } from './preamble';
 import { generateCommandReference, generateSnapshotFlags, generateBrowseSetup } from './browse';
-import { generateDesignMethodology, generateDesignHardRules, generateDesignOutsideVoices, generateDesignReviewLite, generateDesignSketch, generateDesignSetup, generateDesignMockup, generateDesignShotgunLoop } from './design';
+import { generateDesignMethodology, generateDesignHardRules, generateDesignOutsideVoices, generateDesignReviewLite, generateDesignSketch, generateDesignSetup, generateDesignMockup, generateDesignShotgunLoop, generateTasteProfile } from './design';
 import { generateTestBootstrap, generateTestCoverageAuditPlan, generateTestCoverageAuditShip, generateTestCoverageAuditReview } from './testing';
 import { generateReviewDashboard, generatePlanFileReviewReport, generateSpecReviewLoop, generateBenefitsFrom, generateCodexSecondOpinion, generateAdversarialStep, generateCodexPlanReview, generatePlanCompletionAuditShip, generatePlanCompletionAuditReview, generatePlanVerificationExec, generateScopeDrift, generateCrossReviewDedup } from './review';
 import { generateSlugEval, generateSlugSetup, generateBaseBranchDetect, generateDeployBootstrap, generateQAMethodology, generateCoAuthorTrailer, generateChangelogWorkflow } from './utility';
@@ -64,4 +64,6 @@ export const RESOLVERS: Record<string, ResolverFn> = {
   CROSS_REVIEW_DEDUP: generateCrossReviewDedup,
   DX_FRAMEWORK: generateDxFramework,
   MODEL_OVERLAY: generateModelOverlay,
+  TASTE_PROFILE: generateTasteProfile,
+  BIN_DIR: (ctx) => ctx.paths.binDir,
 };