diff --git a/.workflows/solve-issue.yaml b/.workflows/solve-issue.yaml
index 6f9297b..ae1aacf 100644
--- a/.workflows/solve-issue.yaml
+++ b/.workflows/solve-issue.yaml
@@ -154,25 +154,43 @@ conditions:
 graph:
   $START:
     - role: "planner"
+      condition: null
+      prompt: "Analyze the issue and produce an implementation plan."
   planner:
     - role: "$END"
       condition: "insufficientInfo"
+      prompt: "Insufficient information to proceed; end the workflow."
     - role: "developer"
+      condition: null
+      prompt: "Implement the plan from the planner."
   developer:
     - role: "$END"
       condition: "devFailed"
+      prompt: "Development failed; end the workflow."
     - role: "reviewer"
+      condition: null
+      prompt: "Send the implementation to the reviewer."
   reviewer:
     - role: "developer"
       condition: "rejected"
+      prompt: "Reviewer rejected the implementation; fix the issues."
     - role: "tester"
+      condition: null
+      prompt: "Review passed; run tests on the implementation."
   tester:
     - role: "developer"
       condition: "fixCode"
+      prompt: "Tests found code issues; return to developer."
     - role: "planner"
       condition: "fixSpec"
+      prompt: "Tests found spec issues; return to planner."
     - role: "committer"
+      condition: null
+      prompt: "Tests passed; commit and push the changes."
   committer:
     - role: "developer"
       condition: "hookFailed"
+      prompt: "Push hook failed; return to developer to fix."
     - role: "$END"
+      condition: null
+      prompt: "Commit succeeded; complete the workflow."
diff --git a/examples/analyze-topic.yaml b/examples/analyze-topic.yaml
index 9ddb143..118881a 100644
--- a/examples/analyze-topic.yaml
+++ b/examples/analyze-topic.yaml
@@ -36,6 +36,8 @@ graph:
   $START:
     - role: "analyst"
       condition: null
+      prompt: "Analyze the topic in the task and produce a structured summary with key points."
   analyst:
     - role: "$END"
       condition: null
+      prompt: "Analysis complete. Finish the workflow."
diff --git a/examples/solve-issue.yaml b/examples/solve-issue.yaml
index fd793e8..f286794 100644
--- a/examples/solve-issue.yaml
+++ b/examples/solve-issue.yaml
@@ -62,19 +62,19 @@ graph:
   $START:
     - role: "planner"
       condition: null
-      prompt: null
+      prompt: "Analyze the issue described in the task and produce a detailed implementation plan."
   planner:
     - role: "developer"
       condition: null
-      prompt: null
+      prompt: "Implement the plan from the planner. Write code, tests, and ensure existing tests pass."
   developer:
     - role: "reviewer"
       condition: null
-      prompt: null
+      prompt: "Review the developer's implementation against the plan for correctness and quality."
   reviewer:
     - role: "developer"
       condition: "notApproved"
       prompt: "The reviewer rejected your implementation. Read their feedback and fix the issues."
     - role: "$END"
       condition: null
-      prompt: null
+      prompt: "The review passed. Complete the workflow."
diff --git a/packages/cli-workflow/src/commands/thread.ts b/packages/cli-workflow/src/commands/thread.ts
index ed54c1e..d3db13c 100644
--- a/packages/cli-workflow/src/commands/thread.ts
+++ b/packages/cli-workflow/src/commands/thread.ts
@@ -624,12 +624,14 @@ function resolveAgentConfig(
   return agentConfig;
 }
 
-function spawnAgent(agent: AgentConfig, threadId: ThreadId, role: string, edgePrompt: string | null): CasRef {
+function spawnAgent(
+  agent: AgentConfig,
+  threadId: ThreadId,
+  role: string,
+  edgePrompt: string,
+): CasRef {
   const argv = [...agent.args, threadId, role];
-  const env = { ...process.env };
-  if (edgePrompt !== null) {
-    env.UWF_EDGE_PROMPT = edgePrompt;
-  }
+  const env = { ...process.env, UWF_EDGE_PROMPT: edgePrompt };
   let stdout: string;
   try {
     stdout = execFileSync(agent.command, argv, {
diff --git a/packages/cli-workflow/src/commands/workflow.ts b/packages/cli-workflow/src/commands/workflow.ts
index c0ec891..23c8368 100644
--- a/packages/cli-workflow/src/commands/workflow.ts
+++ b/packages/cli-workflow/src/commands/workflow.ts
@@ -55,11 +55,16 @@ function isJsonSchema(value: unknown): value is JSONSchema {
 function normalizeGraph(graph: Record<string, Transition[]>): Record<string, Transition[]> {
   const result: Record<string, Transition[]> = {};
   for (const [node, transitions] of Object.entries(graph)) {
-    result[node] = transitions.map((t) => ({
-      role: t.role,
-      condition: t.condition ?? null,
-      prompt: t.prompt ?? null,
-    }));
+    result[node] = transitions.map((t) => {
+      if (typeof t.prompt !== "string" || t.prompt.trim() === "") {
+        fail(`graph[${node}] transition to "${t.role}": prompt is required (non-empty string)`);
+      }
+      return {
+        role: t.role,
+        condition: t.condition ?? null,
+        prompt: t.prompt,
+      };
+    });
   }
   return result;
 }
diff --git a/packages/cli-workflow/src/validate.ts b/packages/cli-workflow/src/validate.ts
index 6cffdef..61dffd2 100644
--- a/packages/cli-workflow/src/validate.ts
+++ b/packages/cli-workflow/src/validate.ts
@@ -44,6 +44,8 @@ function isTransition(value: unknown): boolean {
   const condition = value.condition;
   return (
     typeof value.role === "string" &&
+    typeof value.prompt === "string" &&
+    value.prompt.trim() !== "" &&
     (condition === null || condition === undefined || typeof condition === "string")
   );
 }
diff --git a/packages/workflow-agent-claude-code/__tests__/claude-code.test.ts b/packages/workflow-agent-claude-code/__tests__/claude-code.test.ts
index 4e9f5ee..952252c 100644
--- a/packages/workflow-agent-claude-code/__tests__/claude-code.test.ts
+++ b/packages/workflow-agent-claude-code/__tests__/claude-code.test.ts
@@ -1,9 +1,12 @@
 import { describe, expect, test } from "bun:test";
 import type { AgentContext } from "@uncaged/workflow-agent-kit";
+import type { ThreadId } from "@uncaged/workflow-protocol";
 import { buildClaudeCodePrompt } from "../src/claude-code.js";
 
 function makeCtx(overrides: Partial<AgentContext> = {}): AgentContext {
   return {
+    threadId: "01JTEST0000000000000000000" as ThreadId,
+    edgePrompt: "Proceed with the assigned role.",
     workflow: {
       roles: {
         developer: {
diff --git a/packages/workflow-agent-hermes/src/hermes.ts b/packages/workflow-agent-hermes/src/hermes.ts
index a1ba4c5..f65b777 100644
--- a/packages/workflow-agent-hermes/src/hermes.ts
+++ b/packages/workflow-agent-hermes/src/hermes.ts
@@ -50,7 +50,7 @@ function buildInitialPrompt(ctx: AgentContext): string {
 
 /** Assemble system prompt, task, and prior step outputs for Hermes. */
 export function buildHermesPrompt(ctx: AgentContext): string {
-  if (ctx.edgePrompt !== null) {
+  if (ctx.edgePrompt !== "") {
     const parts: string[] = [];
     if (ctx.outputFormatInstruction !== "") {
       parts.push(ctx.outputFormatInstruction, "");
@@ -86,7 +86,7 @@ async function prepareSession(
   ctx: AgentContext,
   cwd: string,
 ): Promise<PromptAttempt> {
-  if (ctx.edgePrompt === null || isResumeDisabled()) {
+  if (ctx.edgePrompt === "" || isResumeDisabled()) {
     await client.connect(cwd);
     return { useContinuation: false, resumed: false };
   }
@@ -127,7 +127,7 @@ export function createHermesAgent(): () => Promise<void> {
   });
 
   async function runPrompt(ctx: AgentContext, useContinuation: boolean): Promise<AgentRunResult> {
-    const effectiveCtx = useContinuation ? ctx : { ...ctx, edgePrompt: null as string | null };
+    const effectiveCtx = useContinuation ? ctx : { ...ctx, edgePrompt: "" };
     const fullPrompt = buildHermesPrompt(effectiveCtx);
     const { text, sessionId, messages } = await client.prompt(fullPrompt);
     const { detailHash } = await storePromptResult(ctx.store, sessionId, messages);
diff --git a/packages/workflow-agent-kit/src/context.ts b/packages/workflow-agent-kit/src/context.ts
index bd4943d..2ea1a02 100644
--- a/packages/workflow-agent-kit/src/context.ts
+++ b/packages/workflow-agent-kit/src/context.ts
@@ -21,6 +21,14 @@ function fail(message: string): never {
   throw new Error(message);
 }
 
+function readEdgePrompt(): string {
+  const value = process.env.UWF_EDGE_PROMPT;
+  if (value === undefined || value === "") {
+    fail("UWF_EDGE_PROMPT environment variable is required");
+  }
+  return value;
+}
+
 function walkChain(store: Store, schemas: AgentStore["schemas"], headHash: CasRef): ChainState {
   const headNode = store.get(headHash);
   if (headNode === null) {
@@ -133,7 +141,7 @@ export async function buildContext(threadId: ThreadId, role: string): Promise<Ag
   }
 
   const steps = await buildHistory(store, chain.stepsNewestFirst);
-  const edgePrompt = process.env.UWF_EDGE_PROMPT ?? null;
+  const edgePrompt = readEdgePrompt();
 
   return {
     threadId,
@@ -180,7 +188,7 @@ export async function buildContextWithMeta(
   }
 
   const steps = await buildHistory(store, chain.stepsNewestFirst);
-  const edgePrompt = process.env.UWF_EDGE_PROMPT ?? null;
+  const edgePrompt = readEdgePrompt();
 
   return {
     threadId,
diff --git a/packages/workflow-agent-kit/src/types.ts b/packages/workflow-agent-kit/src/types.ts
index c0ba8a8..c68a79f 100644
--- a/packages/workflow-agent-kit/src/types.ts
+++ b/packages/workflow-agent-kit/src/types.ts
@@ -13,11 +13,10 @@ export type AgentContext = ModeratorContext & {
    */
   outputFormatInstruction: string;
   /**
-   * Edge prompt from the graph transition that led to this role.
-   * null on first entry (use full role definition), non-null on re-entry
-   * (use as continuation instruction from moderator).
+   * Edge prompt from the graph transition that led to this role (UWF_EDGE_PROMPT).
+   * Phase 2 will use visit history to choose full role definition vs continuation.
    */
-  edgePrompt: string | null;
+  edgePrompt: string;
 };
 
 export type AgentRunResult = {
diff --git a/packages/workflow-dashboard/server/workflow.ts b/packages/workflow-dashboard/server/workflow.ts
index 97979af..4580c04 100644
--- a/packages/workflow-dashboard/server/workflow.ts
+++ b/packages/workflow-dashboard/server/workflow.ts
@@ -77,9 +77,11 @@ function stepsToPayload(name: string, description: string, steps: WorkFlowSteps)
           };
         }
       }
+      const targetRole = t.target === "END" ? "$END" : t.target;
       return {
-        role: t.target === "END" ? "$END" : t.target,
+        role: targetRole,
         condition: condName,
+        prompt: `Transition to ${targetRole}.`,
       };
     });
 
@@ -87,7 +89,14 @@ function stepsToPayload(name: string, description: string, steps: WorkFlowSteps)
   }
 
   if (steps.length > 0) {
-    graph["$START"] = [{ role: steps[0].role.name, condition: null }];
+    const firstRole = steps[0].role.name;
+    graph["$START"] = [
+      {
+        role: firstRole,
+        condition: null,
+        prompt: `Begin workflow at role ${firstRole}.`,
+      },
+    ];
   }
 
   return { name, description, roles, conditions, graph };
diff --git a/packages/workflow-moderator/__tests__/evaluate.test.ts b/packages/workflow-moderator/__tests__/evaluate.test.ts
index 6cf4872..dcb7656 100644
--- a/packages/workflow-moderator/__tests__/evaluate.test.ts
+++ b/packages/workflow-moderator/__tests__/evaluate.test.ts
@@ -9,27 +9,27 @@ const solveIssueWorkflow: WorkflowPayload = {
   roles: {
     planner: {
       description: "Creates implementation plan",
-      identity: "You are a planning agent.",
-      prepare: "Review the issue context.",
-      execute: "Create a step-by-step plan.",
-      report: "Output the plan and steps.",
-      outputSchema: "5GWKR8TN1V3JA",
+      goal: "You are a planning agent.",
+      capabilities: ["planning"],
+      procedure: "Create a step-by-step plan.",
+      output: "Output the plan and steps.",
+      frontmatter: "5GWKR8TN1V3JA",
     },
     developer: {
       description: "Implements code changes",
-      identity: "You are a developer agent.",
-      prepare: "Load coding tools.",
-      execute: "Implement the plan.",
-      report: "List files changed and summary.",
-      outputSchema: "8CNWT4KR6D1HV",
+      goal: "You are a developer agent.",
+      capabilities: ["coding"],
+      procedure: "Implement the plan.",
+      output: "List files changed and summary.",
+      frontmatter: "8CNWT4KR6D1HV",
     },
     reviewer: {
       description: "Reviews code changes",
-      identity: "You are a code reviewer.",
-      prepare: "Review project conventions.",
-      execute: "Review the implementation.",
-      report: "Approve or reject with comments.",
-      outputSchema: "1VPBG9SM5E7WK",
+      goal: "You are a code reviewer.",
+      capabilities: ["code-review"],
+      procedure: "Review the implementation.",
+      output: "Approve or reject with comments.",
+      frontmatter: "1VPBG9SM5E7WK",
     },
   },
   conditions: {
@@ -43,15 +43,35 @@ const solveIssueWorkflow: WorkflowPayload = {
     },
   },
   graph: {
-    $START: [{ role: "planner", condition: null }],
-    planner: [
-      { role: "developer", condition: "needsClarification" },
-      { role: "$END", condition: null },
+    $START: [
+      {
+        role: "planner",
+        condition: null,
+        prompt: "Start planning from the issue in the task.",
+      },
+    ],
+    planner: [
+      {
+        role: "developer",
+        condition: "needsClarification",
+        prompt: "Clarification is needed; hand off to developer.",
+      },
+      { role: "$END", condition: null, prompt: "Planning complete; end workflow." },
+    ],
+    developer: [
+      {
+        role: "reviewer",
+        condition: null,
+        prompt: "Implementation done; send to reviewer.",
+      },
     ],
-    developer: [{ role: "reviewer", condition: null }],
     reviewer: [
-      { role: "developer", condition: "rejected" },
-      { role: "$END", condition: null },
+      {
+        role: "developer",
+        condition: "rejected",
+        prompt: "Reviewer rejected; return to developer.",
+      },
+      { role: "$END", condition: null, prompt: "Review passed; end workflow." },
     ],
   },
 };
@@ -69,7 +89,10 @@ function makeContext(steps: ModeratorContext["steps"]): ModeratorContext {
 describe("evaluate", () => {
   test("$START → first role (fallback)", async () => {
     const result = await evaluate(solveIssueWorkflow, makeContext([]));
-    expect(result).toEqual({ ok: true, value: { role: "planner", prompt: null } });
+    expect(result).toEqual({
+      ok: true,
+      value: { role: "planner", prompt: "Start planning from the issue in the task." },
+    });
   });
 
   test("condition match (rejected → developer)", async () => {
@@ -82,7 +105,10 @@ describe("evaluate", () => {
       },
     ]);
     const result = await evaluate(solveIssueWorkflow, context);
-    expect(result).toEqual({ ok: true, value: { role: "developer", prompt: null } });
+    expect(result).toEqual({
+      ok: true,
+      value: { role: "developer", prompt: "Reviewer rejected; return to developer." },
+    });
   });
 
   test("fallback when condition does not match → $END", async () => {
@@ -95,7 +121,10 @@ describe("evaluate", () => {
       },
     ]);
     const result = await evaluate(solveIssueWorkflow, context);
-    expect(result).toEqual({ ok: true, value: { role: "$END", prompt: null } });
+    expect(result).toEqual({
+      ok: true,
+      value: { role: "$END", prompt: "Review passed; end workflow." },
+    });
   });
 
   test("missing role in graph → error", async () => {
@@ -124,7 +153,10 @@ describe("evaluate", () => {
       },
     ]);
     const result = await evaluate(solveIssueWorkflow, context);
-    expect(result).toEqual({ ok: true, value: { role: "developer", prompt: null } });
+    expect(result).toEqual({
+      ok: true,
+      value: { role: "developer", prompt: "Clarification is needed; hand off to developer." },
+    });
   });
 
   test("$last returns most recent matching role's frontmatter", async () => {
@@ -137,10 +169,20 @@ describe("evaluate", () => {
         },
       },
       graph: {
-        $START: [{ role: "developer", condition: null }],
+        $START: [
+          {
+            role: "developer",
+            condition: null,
+            prompt: "Begin development.",
+          },
+        ],
         developer: [
-          { role: "$END", condition: "devFailed" },
-          { role: "reviewer", condition: null },
+          { role: "$END", condition: "devFailed", prompt: "Development failed; end." },
+          {
+            role: "reviewer",
+            condition: null,
+            prompt: "Development succeeded; review.",
+          },
         ],
       },
     };
@@ -165,7 +207,10 @@ describe("evaluate", () => {
       },
     ]);
     const result = await evaluate(workflow, context);
-    expect(result).toEqual({ ok: true, value: { role: "$END", prompt: null } });
+    expect(result).toEqual({
+      ok: true,
+      value: { role: "$END", prompt: "Development failed; end." },
+    });
   });
 
   test("$first returns earliest matching role's frontmatter", async () => {
@@ -178,10 +223,20 @@ describe("evaluate", () => {
         },
       },
       graph: {
-        $START: [{ role: "planner", condition: null }],
+        $START: [
+          {
+            role: "planner",
+            condition: null,
+            prompt: "Begin planning.",
+          },
+        ],
         planner: [
-          { role: "$END", condition: "firstPlanReady" },
-          { role: "developer", condition: null },
+          { role: "$END", condition: "firstPlanReady", prompt: "First plan was ready; end." },
+          {
+            role: "developer",
+            condition: null,
+            prompt: "Plan not ready on first pass; implement.",
+          },
         ],
       },
     };
@@ -206,7 +261,10 @@ describe("evaluate", () => {
       },
     ]);
     const result = await evaluate(workflow, context);
-    expect(result).toEqual({ ok: true, value: { role: "$END", prompt: null } });
+    expect(result).toEqual({
+      ok: true,
+      value: { role: "$END", prompt: "First plan was ready; end." },
+    });
   });
 
   test("$last returns undefined for unmatched role", async () => {
@@ -219,10 +277,20 @@ describe("evaluate", () => {
         },
       },
       graph: {
-        $START: [{ role: "planner", condition: null }],
+        $START: [
+          {
+            role: "planner",
+            condition: null,
+            prompt: "Begin planning.",
+          },
+        ],
         planner: [
-          { role: "$END", condition: "hasReviewer" },
-          { role: "developer", condition: null },
+          { role: "$END", condition: "hasReviewer", prompt: "Reviewer already ran; end." },
+          {
+            role: "developer",
+            condition: null,
+            prompt: "No reviewer yet; implement.",
+          },
         ],
       },
     };
@@ -236,6 +304,9 @@ describe("evaluate", () => {
     ]);
     const result = await evaluate(workflow, context);
     // no reviewer step → $exists returns false → fallback to developer
-    expect(result).toEqual({ ok: true, value: { role: "developer", prompt: null } });
+    expect(result).toEqual({
+      ok: true,
+      value: { role: "developer", prompt: "No reviewer yet; implement." },
+    });
   });
 });
diff --git a/packages/workflow-moderator/src/evaluate.ts b/packages/workflow-moderator/src/evaluate.ts
index c2ffa9a..a515cd0 100644
--- a/packages/workflow-moderator/src/evaluate.ts
+++ b/packages/workflow-moderator/src/evaluate.ts
@@ -90,7 +90,7 @@ export async function evaluate(
 
   for (const transition of transitions) {
     if (transition.condition === null) {
-      return { ok: true, value: { role: transition.role, prompt: transition.prompt ?? null } };
+      return { ok: true, value: { role: transition.role, prompt: transition.prompt } };
     }
 
     const conditionDef = workflow.conditions[transition.condition];
@@ -106,7 +106,7 @@ export async function evaluate(
       return evalResult;
     }
     if (isTruthy(evalResult.value)) {
-      return { ok: true, value: { role: transition.role, prompt: transition.prompt ?? null } };
+      return { ok: true, value: { role: transition.role, prompt: transition.prompt } };
     }
   }
 
diff --git a/packages/workflow-moderator/src/types.ts b/packages/workflow-moderator/src/types.ts
index 0d09297..77599f0 100644
--- a/packages/workflow-moderator/src/types.ts
+++ b/packages/workflow-moderator/src/types.ts
@@ -1,7 +1,7 @@
 export type Result<T, E> = { ok: true; value: T } | { ok: false; error: E };
 
-/** The result of moderator evaluation — which role to go to, and the edge prompt (if any). */
+/** The result of moderator evaluation — which role to go to, and the edge prompt. */
 export type EvaluateResult = {
   role: string;
-  prompt: string | null;
+  prompt: string;
 };
diff --git a/packages/workflow-protocol/src/schemas.ts b/packages/workflow-protocol/src/schemas.ts
index cb28471..09ed1aa 100644
--- a/packages/workflow-protocol/src/schemas.ts
+++ b/packages/workflow-protocol/src/schemas.ts
@@ -26,10 +26,11 @@ const CONDITION_DEFINITION: JSONSchema = {
 
 const TRANSITION: JSONSchema = {
   type: "object",
-  required: ["role", "condition"],
+  required: ["role", "condition", "prompt"],
   properties: {
     role: { type: "string" },
     condition: { anyOf: [{ type: "string" }, { type: "null" }] },
+    prompt: { type: "string" },
   },
   additionalProperties: false,
 };
diff --git a/packages/workflow-protocol/src/types.ts b/packages/workflow-protocol/src/types.ts
index 86b1a09..1dcd822 100644
--- a/packages/workflow-protocol/src/types.ts
+++ b/packages/workflow-protocol/src/types.ts
@@ -28,7 +28,7 @@ export type RoleDefinition = {
 export type Transition = {
   role: string;
   condition: string | null;
-  prompt: string | null;
+  prompt: string;
 };
 
 export type ConditionDefinition = {