fix(model-routing): use honest unitTypes for discuss dispatches and map all auto-dispatch phases

Discuss dispatches in guided-flow.ts were aliased to "plan-milestone"/"plan-slice"
unitTypes, causing the planning model preference to silently override the user's
active model. This was discovered when a user configured Codex as their model but
got switched to Opus during discuss phases because models.planning was set.

Changes:
- Add "discuss" and "validation" keys to GSDModelConfig/GSDModelConfigV2
- Map discuss-milestone/discuss-slice to models.discuss (falls back to planning)
- Map reassess-roadmap/rewrite-docs/gate-evaluate/validate-milestone to
  models.validation (falls back to planning)
- Map reactive-execute to models.execution, complete-milestone to models.completion
- Fix 15 dispatchWorkflow calls in guided-flow.ts to use honest unitTypes
- Add discuss-slice to LIFECYCLE_ONLY_UNITS, artifact paths, metrics phase
  classification, complexity tiers, and all dashboard/overlay label functions

Closes #2865

src/resources/extensions/gsd/auto-artifact-paths.ts

@@ -30,6 +30,10 @@ export function resolveExpectedArtifactPath(
       const dir = resolveMilestonePath(base, mid);
       return dir ? join(dir, buildMilestoneFileName(mid, "CONTEXT")) : null;
     }
+    case "discuss-slice": {
+      const dir = resolveSlicePath(base, mid, sid!);
+      return dir ? join(dir, buildSliceFileName(sid!, "CONTEXT")) : null;
+    }
     case "research-milestone": {
       const dir = resolveMilestonePath(base, mid);
       return dir ? join(dir, buildMilestoneFileName(mid, "RESEARCH")) : null;
@@ -98,6 +102,8 @@ export function diagnoseExpectedArtifact(
   switch (unitType) {
     case "discuss-milestone":
       return `${relMilestoneFile(base, mid, "CONTEXT")} (milestone context from discussion)`;
+    case "discuss-slice":
+      return `${relSliceFile(base, mid, sid!, "CONTEXT")} (slice context from discussion)`;
     case "research-milestone":
       return `${relMilestoneFile(base, mid, "RESEARCH")} (milestone research)`;
     case "plan-milestone":

src/resources/extensions/gsd/auto-dashboard.ts

@@ -77,7 +77,8 @@ export interface AutoDashboardData {
 export function unitVerb(unitType: string): string {
   if (unitType.startsWith("hook/")) return `hook: ${unitType.slice(5)}`;
   switch (unitType) {
-    case "discuss-milestone": return "discussing";
+    case "discuss-milestone":
+    case "discuss-slice": return "discussing";
     case "research-milestone":
     case "research-slice": return "researching";
     case "plan-milestone":
@@ -96,7 +97,8 @@ export function unitVerb(unitType: string): string {
 export function unitPhaseLabel(unitType: string): string {
   if (unitType.startsWith("hook/")) return "HOOK";
   switch (unitType) {
-    case "discuss-milestone": return "DISCUSS";
+    case "discuss-milestone":
+    case "discuss-slice": return "DISCUSS";
     case "research-milestone": return "RESEARCH";
     case "research-slice": return "RESEARCH";
     case "plan-milestone": return "PLAN";
@@ -123,6 +125,7 @@ function peekNext(unitType: string, state: GSDState): string {
   if (unitType.startsWith("hook/")) return `continue ${sid}`;
   switch (unitType) {
     case "discuss-milestone": return "research or plan milestone";
+    case "discuss-slice": return "plan slice";
     case "research-milestone": return "plan milestone roadmap";
     case "plan-milestone": return "plan or execute first slice";
     case "research-slice": return `plan ${sid}`;

src/resources/extensions/gsd/auto-post-unit.ts

@@ -74,7 +74,7 @@ function enqueueSidecar(
  *  Auto-commit is skipped for these — their state files are picked up by the
  *  next actual task commit via `smartStage()`. */
 const LIFECYCLE_ONLY_UNITS = new Set([
-  "research-milestone", "discuss-milestone", "plan-milestone",
+  "research-milestone", "discuss-milestone", "discuss-slice", "plan-milestone",
   "validate-milestone", "research-slice", "plan-slice",
   "replan-slice", "complete-slice", "run-uat",
   "reassess-roadmap", "rewrite-docs",

src/resources/extensions/gsd/complexity-classifier.ts

@@ -37,6 +37,7 @@ const UNIT_TYPE_TIERS: Record<string, ComplexityTier> = {
 
   // Tier 2 — Standard: research, routine planning, discussion
   "discuss-milestone": "standard",
+  "discuss-slice": "standard",
   "research-milestone": "standard",
   "research-slice": "standard",
   "plan-milestone": "standard",

src/resources/extensions/gsd/dashboard-overlay.ts

@@ -29,6 +29,8 @@ import { runEnvironmentChecks, type EnvironmentCheckResult } from "./doctor-envi
 
 function unitLabel(type: string): string {
   switch (type) {
+    case "discuss-milestone":
+    case "discuss-slice": return "Discuss";
     case "research-milestone": return "Research";
     case "plan-milestone": return "Plan";
     case "research-slice": return "Research";

src/resources/extensions/gsd/docs/preferences-reference.md

@@ -102,12 +102,14 @@ Setting `prefer_skills: []` does **not** disable skill discovery — it just mea
 
 - `custom_instructions`: extra durable instructions related to skill use. For operational project knowledge (recurring rules, gotchas, patterns), use `.gsd/KNOWLEDGE.md` instead — it's injected into every agent prompt automatically and agents can append to it during execution.
 
-- `models`: per-stage model selection for auto-mode. Keys: `research`, `planning`, `execution`, `execution_simple`, `completion`, `subagent`. Values can be:
+- `models`: per-stage model selection (applies to both auto-mode and guided-flow dispatches). Keys: `research`, `planning`, `discuss`, `execution`, `execution_simple`, `completion`, `validation`, `subagent`. Values can be:
   - Simple string: `"claude-sonnet-4-6"` — single model, no fallbacks
   - Provider-qualified string: `"bedrock/claude-sonnet-4-6"` — targets a specific provider when the same model ID exists across multiple providers
   - Object with fallbacks: `{ model: "claude-opus-4-6", fallbacks: ["glm-5", "minimax-m2.5"] }` — tries fallbacks in order if primary fails
   - Object with provider: `{ model: "claude-opus-4-6", provider: "bedrock" }` — explicit provider targeting in object format
-  - Omit a key to use whatever model is currently active. Fallbacks are tried when model switching fails (provider unavailable, rate limited, etc.).
+  - Omit a key to use whatever model is currently active (except `discuss` and `validation` which fall back to `planning` when unset). Fallbacks are tried when model switching fails (provider unavailable, rate limited, etc.).
+  - `discuss` — used for milestone/slice discussion (interactive context gathering). Falls back to `planning` if unset.
+  - `validation` — used for gate evaluation, roadmap reassessment, milestone validation, and doc rewrites. Falls back to `planning` if unset.
 
 - `skill_staleness_days`: number — skills unused for this many days get deprioritized during discovery. Set to `0` to disable staleness tracking. Default: `60`.
 

src/resources/extensions/gsd/guided-flow.ts

@@ -211,7 +211,7 @@ type UIContext = ExtensionContext;
  * This is the only way the wizard triggers work — everything else is the LLM's job.
  *
  * When a unitType is provided, resolves the user's model preference for that
- * phase (e.g., models.planning → "plan-milestone") and applies it before
+ * phase (e.g., models.planning → "plan-milestone", models.discuss → "discuss-milestone") and applies it before
  * dispatching. This ensures guided-flow dispatches respect the same
  * per-phase model preferences that auto-mode uses.
  */
@@ -573,7 +573,7 @@ export async function showDiscuss(
         ? `${basePrompt}\n\n## Prior Discussion (Draft Seed)\n\n${draftContent}`
         : basePrompt;
       pendingAutoStart = { ctx, pi, basePath, milestoneId: mid, step: false };
-      await dispatchWorkflow(pi, seed, "gsd-discuss", ctx, "plan-milestone");
+      await dispatchWorkflow(pi, seed, "gsd-discuss", ctx, "discuss-milestone");
     } else if (choice === "discuss_fresh") {
       const discussMilestoneTemplates = inlineTemplate("context", "Context");
       const structuredQuestionsAvailable = pi.getActiveTools().includes("ask_user_questions") ? "true" : "false";
@@ -581,13 +581,13 @@ export async function showDiscuss(
       await dispatchWorkflow(pi, loadPrompt("guided-discuss-milestone", {
         milestoneId: mid, milestoneTitle, inlinedTemplates: discussMilestoneTemplates, structuredQuestionsAvailable,
         commitInstruction: buildDocsCommitInstruction(`docs(${mid}): milestone context from discuss`),
-      }), "gsd-discuss", ctx, "plan-milestone");
+      }), "gsd-discuss", ctx, "discuss-milestone");
     } else if (choice === "skip_milestone") {
       const milestoneIds = findMilestoneIds(basePath);
       const uniqueMilestoneIds = !!loadEffectiveGSDPreferences()?.preferences?.unique_milestone_ids;
       const nextId = nextMilestoneIdReserved(milestoneIds, uniqueMilestoneIds);
       pendingAutoStart = { ctx, pi, basePath, milestoneId: nextId, step: false };
-      await dispatchWorkflow(pi, buildDiscussPrompt(nextId, `New milestone ${nextId}.`, basePath), "gsd-run", ctx, "plan-milestone");
+      await dispatchWorkflow(pi, buildDiscussPrompt(nextId, `New milestone ${nextId}.`, basePath), "gsd-run", ctx, "discuss-milestone");
     }
     return;
   }
@@ -717,7 +717,7 @@ export async function showDiscuss(
     }
 
     const prompt = await buildDiscussSlicePrompt(mid, chosen.id, chosen.title, basePath, { rediscuss: isRediscuss });
-    await dispatchWorkflow(pi, prompt, "gsd-discuss", ctx, "plan-slice");
+    await dispatchWorkflow(pi, prompt, "gsd-discuss", ctx, "discuss-slice");
 
     // Wait for the discuss session to finish, then loop back to the picker
     await ctx.waitForIdle();
@@ -795,7 +795,7 @@ async function dispatchDiscussForMilestone(
   const prompt = draftContent
     ? `${basePrompt}\n\n## Prior Discussion (Draft Seed)\n\n${draftContent}`
     : basePrompt;
-  await dispatchWorkflow(pi, prompt, "gsd-discuss", ctx, "plan-milestone");
+  await dispatchWorkflow(pi, prompt, "gsd-discuss", ctx, "discuss-milestone");
 }
 
 // ─── Smart Entry Point ────────────────────────────────────────────────────────
@@ -935,7 +935,7 @@ async function handleMilestoneActions(
     await dispatchWorkflow(pi, buildDiscussPrompt(nextId,
       `New milestone ${nextId}.`,
       basePath
-    ), "gsd-run", ctx, "plan-milestone");
+    ), "gsd-run", ctx, "discuss-milestone");
     return true;
   }
 
@@ -1086,7 +1086,7 @@ export async function showSmartEntry(
       await dispatchWorkflow(pi, buildDiscussPrompt(nextId,
         `New project, milestone ${nextId}. Do NOT read or explore .gsd/ — it's empty scaffolding.`,
         basePath
-      ), "gsd-run", ctx, "plan-milestone");
+      ), "gsd-run", ctx, "discuss-milestone");
     } else {
       const choice = await showNextAction(ctx, {
         title: "GSD — Get Shit Done",
@@ -1107,7 +1107,7 @@ export async function showSmartEntry(
         await dispatchWorkflow(pi, buildDiscussPrompt(nextId,
           `New milestone ${nextId}.`,
           basePath
-        ), "gsd-run", ctx, "plan-milestone");
+        ), "gsd-run", ctx, "discuss-milestone");
       }
     }
     return;
@@ -1146,7 +1146,7 @@ export async function showSmartEntry(
       await dispatchWorkflow(pi, buildDiscussPrompt(nextId,
         `New milestone ${nextId}.`,
         basePath
-      ), "gsd-run", ctx, "plan-milestone");
+      ), "gsd-run", ctx, "discuss-milestone");
     } else if (choice === "status") {
       const { fireStatusViaCommand } = await import("./commands.js");
       await fireStatusViaCommand(ctx);
@@ -1194,7 +1194,7 @@ export async function showSmartEntry(
         ? `${basePrompt}\n\n## Prior Discussion (Draft Seed)\n\n${draftContent}`
         : basePrompt;
       pendingAutoStart = { ctx, pi, basePath, milestoneId, step: stepMode };
-      await dispatchWorkflow(pi, seed, "gsd-discuss", ctx, "plan-milestone");
+      await dispatchWorkflow(pi, seed, "gsd-discuss", ctx, "discuss-milestone");
     } else if (choice === "discuss_fresh") {
       const discussMilestoneTemplates = inlineTemplate("context", "Context");
       const structuredQuestionsAvailable = pi.getActiveTools().includes("ask_user_questions") ? "true" : "false";
@@ -1202,7 +1202,7 @@ export async function showSmartEntry(
       await dispatchWorkflow(pi, loadPrompt("guided-discuss-milestone", {
         milestoneId, milestoneTitle, inlinedTemplates: discussMilestoneTemplates, structuredQuestionsAvailable,
         commitInstruction: buildDocsCommitInstruction(`docs(${milestoneId}): milestone context from discuss`),
-      }), "gsd-discuss", ctx, "plan-milestone");
+      }), "gsd-discuss", ctx, "discuss-milestone");
     } else if (choice === "skip_milestone") {
       const milestoneIds = findMilestoneIds(basePath);
       const uniqueMilestoneIds = !!loadEffectiveGSDPreferences()?.preferences?.unique_milestone_ids;
@@ -1211,7 +1211,7 @@ export async function showSmartEntry(
       await dispatchWorkflow(pi, buildDiscussPrompt(nextId,
         `New milestone ${nextId}.`,
         basePath
-      ), "gsd-run", ctx, "plan-milestone");
+      ), "gsd-run", ctx, "discuss-milestone");
     }
     return;
   }
@@ -1286,7 +1286,7 @@ export async function showSmartEntry(
         await dispatchWorkflow(pi, loadPrompt("guided-discuss-milestone", {
           milestoneId, milestoneTitle, inlinedTemplates: discussMilestoneTemplates, structuredQuestionsAvailable,
           commitInstruction: buildDocsCommitInstruction(`docs(${milestoneId}): milestone context from discuss`),
-        }), "gsd-run", ctx, "plan-milestone");
+        }), "gsd-run", ctx, "discuss-milestone");
       } else if (choice === "skip_milestone") {
         const milestoneIds = findMilestoneIds(basePath);
         const uniqueMilestoneIds = !!loadEffectiveGSDPreferences()?.preferences?.unique_milestone_ids;
@@ -1295,7 +1295,7 @@ export async function showSmartEntry(
         await dispatchWorkflow(pi, buildDiscussPrompt(nextId,
           `New milestone ${nextId}.`,
           basePath
-        ), "gsd-run", ctx, "plan-milestone");
+        ), "gsd-run", ctx, "discuss-milestone");
       } else if (choice === "discard_milestone") {
         const confirmed = await showConfirm(ctx, {
           title: "Discard milestone?",
@@ -1421,7 +1421,7 @@ export async function showSmartEntry(
         }),
       }), "gsd-run", ctx, "plan-slice");
     } else if (choice === "discuss") {
-      await dispatchWorkflow(pi, await buildDiscussSlicePrompt(milestoneId, sliceId, sliceTitle, basePath, { rediscuss: hasContext }), "gsd-run", ctx, "plan-slice");
+      await dispatchWorkflow(pi, await buildDiscussSlicePrompt(milestoneId, sliceId, sliceTitle, basePath, { rediscuss: hasContext }), "gsd-run", ctx, "discuss-slice");
     } else if (choice === "research") {
       const researchTemplates = inlineTemplate("research", "Research");
       await dispatchWorkflow(pi, loadPrompt("guided-research-slice", {

src/resources/extensions/gsd/metrics.ts

@@ -75,13 +75,16 @@ export interface MetricsLedger {
 
 // ─── Phase classification ─────────────────────────────────────────────────────
 
-export type MetricsPhase = "research" | "planning" | "execution" | "completion" | "reassessment";
+export type MetricsPhase = "research" | "discussion" | "planning" | "execution" | "completion" | "reassessment";
 
 export function classifyUnitPhase(unitType: string): MetricsPhase {
   switch (unitType) {
     case "research-milestone":
     case "research-slice":
       return "research";
+    case "discuss-milestone":
+    case "discuss-slice":
+      return "discussion";
     case "plan-milestone":
     case "plan-slice":
       return "planning";
@@ -299,7 +302,7 @@ export function aggregateByPhase(units: UnitMetrics[]): PhaseAggregate[] {
     agg.duration += u.finishedAt - u.startedAt;
   }
   // Return in a stable order
-  const order: MetricsPhase[] = ["research", "planning", "execution", "completion", "reassessment"];
+  const order: MetricsPhase[] = ["research", "discussion", "planning", "execution", "completion", "reassessment"];
   return order.map(p => map.get(p)).filter((a): a is PhaseAggregate => !!a);
 }
 

src/resources/extensions/gsd/preferences-models.ts

@@ -56,16 +56,28 @@ export function resolveModelWithFallbacksForUnit(unitType: string): ResolvedMode
     case "replan-slice":
       phaseConfig = m.planning;
       break;
+    case "discuss-milestone":
+    case "discuss-slice":
+      phaseConfig = m.discuss ?? m.planning;
+      break;
     case "execute-task":
+    case "reactive-execute":
       phaseConfig = m.execution;
       break;
     case "execute-task-simple":
       phaseConfig = m.execution_simple ?? m.execution;
       break;
     case "complete-slice":
+    case "complete-milestone":
     case "run-uat":
       phaseConfig = m.completion;
       break;
+    case "reassess-roadmap":
+    case "rewrite-docs":
+    case "gate-evaluate":
+    case "validate-milestone":
+      phaseConfig = m.validation ?? m.planning;
+      break;
     default:
       // Subagent unit types (e.g., "subagent", "subagent/scout")
       if (unitType === "subagent" || unitType.startsWith("subagent/")) {

src/resources/extensions/gsd/preferences-types.ts

@@ -134,9 +134,11 @@ export interface GSDPhaseModelConfig {
 export interface GSDModelConfig {
   research?: string;
   planning?: string;
+  discuss?: string;
   execution?: string;
   execution_simple?: string;
   completion?: string;
+  validation?: string;
   subagent?: string;
 }
 
@@ -147,9 +149,11 @@ export interface GSDModelConfig {
 export interface GSDModelConfigV2 {
   research?: string | GSDPhaseModelConfig;
   planning?: string | GSDPhaseModelConfig;
+  discuss?: string | GSDPhaseModelConfig;
   execution?: string | GSDPhaseModelConfig;
   execution_simple?: string | GSDPhaseModelConfig;
   completion?: string | GSDPhaseModelConfig;
+  validation?: string | GSDPhaseModelConfig;
   subagent?: string | GSDPhaseModelConfig;
 }
 

src/resources/extensions/gsd/tests/model-unittype-mapping.test.ts

@@ -0,0 +1,192 @@
+/**
+ * Model UnitType Mapping — regression tests for #2865.
+ *
+ * Verifies that all auto-dispatch unitTypes have corresponding entries in:
+ * - resolveModelWithFallbacksForUnit (preferences-models.ts)
+ * - classifyUnitPhase (metrics.ts)
+ * - LIFECYCLE_ONLY_UNITS (auto-post-unit.ts)
+ * - unitVerb / unitPhaseLabel (auto-dashboard.ts)
+ * - resolveExpectedArtifactPath (auto-artifact-paths.ts)
+ *
+ * Uses source-level checks to avoid import resolution issues in dev.
+ *
+ * Copyright (c) 2026 Jeremy McSpadden <jeremy@fluxlabs.net>
+ */
+
+import test from "node:test";
+import assert from "node:assert/strict";
+import { readFileSync } from "node:fs";
+import { join, dirname } from "node:path";
+import { fileURLToPath } from "node:url";
+
+const __dirname = dirname(fileURLToPath(import.meta.url));
+const gsdDir = join(__dirname, "..");
+
+function readSrc(file: string): string {
+  return readFileSync(join(gsdDir, file), "utf-8");
+}
+
+const preferencesSrc = readSrc("preferences-models.ts");
+const metricsSrc = readSrc("metrics.ts");
+const postUnitSrc = readSrc("auto-post-unit.ts");
+const dashboardSrc = readSrc("auto-dashboard.ts");
+const artifactSrc = readSrc("auto-artifact-paths.ts");
+const guidedFlowSrc = readSrc("guided-flow.ts");
+const autoDispatchSrc = readSrc("auto-dispatch.ts");
+
+// Derive unitTypes directly from auto-dispatch.ts source so the test
+// automatically tracks dispatch rule changes (Copilot review feedback).
+const AUTO_DISPATCH_UNIT_TYPES = (() => {
+  const unitTypeRegex = /unitType:\s*["']([^"']+)["']/g;
+  const unitTypes = new Set<string>();
+  let match: RegExpExecArray | null;
+  while ((match = unitTypeRegex.exec(autoDispatchSrc)) !== null) {
+    unitTypes.add(match[1]);
+  }
+  return Array.from(unitTypes);
+})();
+
+// Additionally include unitTypes used by guided-flow but not auto-dispatch
+// (e.g., discuss-slice is dispatched by guided-flow but not auto-dispatch).
+const ALL_KNOWN_UNIT_TYPES = [
+  ...new Set([...AUTO_DISPATCH_UNIT_TYPES, "discuss-slice"]),
+];
+
+// ═══════════════════════════════════════════════════════════════════════════
+// #2865: discuss dispatches must NOT alias to plan unitTypes
+// ═══════════════════════════════════════════════════════════════════════════
+
+test("#2865: no dispatchWorkflow with gsd-discuss customType uses plan-milestone", () => {
+  // Match dispatchWorkflow calls where "gsd-discuss" appears before "plan-milestone"
+  // in the same call (the 5 args are on consecutive lines).
+  const blocks = guidedFlowSrc.split(/dispatchWorkflow\(/);
+  for (const block of blocks) {
+    const callEnd = block.indexOf(");");
+    if (callEnd === -1) continue;
+    const call = block.slice(0, callEnd);
+    if (call.includes('"gsd-discuss"') && call.includes('"plan-milestone"')) {
+      assert.fail(`Discuss dispatch should not use plan-milestone: ...dispatchWorkflow(${call.slice(0, 120).trim()}...`);
+    }
+  }
+});
+
+test("#2865: no dispatchWorkflow with gsd-discuss customType uses plan-slice", () => {
+  const blocks = guidedFlowSrc.split(/dispatchWorkflow\(/);
+  for (const block of blocks) {
+    const callEnd = block.indexOf(");");
+    if (callEnd === -1) continue;
+    const call = block.slice(0, callEnd);
+    if (call.includes('"gsd-discuss"') && call.includes('"plan-slice"')) {
+      assert.fail(`Discuss slice dispatch should not use plan-slice: ...dispatchWorkflow(${call.slice(0, 120).trim()}...`);
+    }
+  }
+});
+
+test("#2865: no buildDiscussPrompt call dispatches with plan-milestone", () => {
+  const blocks = guidedFlowSrc.split(/dispatchWorkflow\(/);
+  for (const block of blocks) {
+    const callEnd = block.indexOf(");");
+    if (callEnd === -1) continue;
+    const call = block.slice(0, callEnd);
+    if (call.includes("buildDiscussPrompt") && call.includes('"plan-milestone"')) {
+      assert.fail(`buildDiscussPrompt dispatch should not use plan-milestone`);
+    }
+  }
+});
+
+test("#2865: no buildDiscussSlicePrompt call dispatches with plan-slice", () => {
+  const blocks = guidedFlowSrc.split(/dispatchWorkflow\(/);
+  for (const block of blocks) {
+    const callEnd = block.indexOf(");");
+    if (callEnd === -1) continue;
+    const call = block.slice(0, callEnd);
+    if (call.includes("buildDiscussSlicePrompt") && call.includes('"plan-slice"')) {
+      assert.fail(`buildDiscussSlicePrompt dispatch should not use plan-slice`);
+    }
+  }
+});
+
+test("#2865: no guided-discuss-milestone loadPrompt dispatches with plan-milestone", () => {
+  const blocks = guidedFlowSrc.split(/dispatchWorkflow\(/);
+  for (const block of blocks) {
+    const callEnd = block.indexOf(");");
+    if (callEnd === -1) continue;
+    const call = block.slice(0, callEnd);
+    if (call.includes("guided-discuss-milestone") && call.includes('"plan-milestone"')) {
+      assert.fail(`guided-discuss-milestone dispatch should not use plan-milestone`);
+    }
+  }
+});
+
+// ═══════════════════════════════════════════════════════════════════════════
+// preferences-models.ts: resolveModelWithFallbacksForUnit coverage
+// ═══════════════════════════════════════════════════════════════════════════
+
+test("resolveModelWithFallbacksForUnit handles discuss-milestone", () => {
+  assert.ok(preferencesSrc.includes('"discuss-milestone"'), "missing discuss-milestone case");
+});
+
+test("resolveModelWithFallbacksForUnit handles discuss-slice", () => {
+  assert.ok(preferencesSrc.includes('"discuss-slice"'), "missing discuss-slice case");
+});
+
+test("discuss unitTypes fall back to planning when models.discuss is unset", () => {
+  assert.ok(
+    preferencesSrc.includes("m.discuss ?? m.planning"),
+    "discuss should fall back to m.planning",
+  );
+});
+
+test("validation unitTypes fall back to planning when models.validation is unset", () => {
+  assert.ok(
+    preferencesSrc.includes("m.validation ?? m.planning"),
+    "validation should fall back to m.planning",
+  );
+});
+
+test("all auto-dispatch unitTypes have preference mapping or subagent handling", () => {
+  const unmapped: string[] = [];
+  for (const ut of ALL_KNOWN_UNIT_TYPES) {
+    if (!preferencesSrc.includes(`"${ut}"`)) {
+      unmapped.push(ut);
+    }
+  }
+  assert.deepEqual(unmapped, [], `Unmapped unitTypes in preferences-models.ts: ${unmapped.join(", ")}`);
+});
+
+// ═══════════════════════════════════════════════════════════════════════════
+// metrics.ts: classifyUnitPhase coverage
+// ═══════════════════════════════════════════════════════════════════════════
+
+test("classifyUnitPhase includes discussion phase", () => {
+  assert.ok(metricsSrc.includes('"discussion"'), "MetricsPhase should include discussion");
+});
+
+test("classifyUnitPhase maps discuss-milestone and discuss-slice", () => {
+  assert.ok(metricsSrc.includes('"discuss-milestone"'), "missing discuss-milestone in metrics");
+  assert.ok(metricsSrc.includes('"discuss-slice"'), "missing discuss-slice in metrics");
+});
+
+// ═══════════════════════════════════════════════════════════════════════════
+// auto-post-unit.ts: LIFECYCLE_ONLY_UNITS
+// ═══════════════════════════════════════════════════════════════════════════
+
+test("LIFECYCLE_ONLY_UNITS includes discuss-slice", () => {
+  assert.ok(postUnitSrc.includes('"discuss-slice"'), "discuss-slice should be lifecycle-only");
+});
+
+// ═══════════════════════════════════════════════════════════════════════════
+// auto-dashboard.ts: display label coverage
+// ═══════════════════════════════════════════════════════════════════════════
+
+test("unitVerb handles discuss-slice", () => {
+  assert.ok(dashboardSrc.includes('"discuss-slice"'), "missing discuss-slice in dashboard");
+});
+
+// ═══════════════════════════════════════════════════════════════════════════
+// auto-artifact-paths.ts: artifact resolution
+// ═══════════════════════════════════════════════════════════════════════════
+
+test("resolveExpectedArtifactPath handles discuss-slice", () => {
+  assert.ok(artifactSrc.includes('"discuss-slice"'), "missing discuss-slice in artifact paths");
+});