diff --git a/src/agents/prometheus/plan-generation.ts b/src/agents/prometheus/plan-generation.ts
index 152de8472..b93e2d8c5 100644
--- a/src/agents/prometheus/plan-generation.ts
+++ b/src/agents/prometheus/plan-generation.ts
@@ -95,7 +95,9 @@ task(
   4. Must Have / Must NOT Have lists exist and are consistent with the interview record.
   5. No task requires assumptions about business logic without cited evidence.
   6. Plan path is .omo/plans/, not docs/ or plans/.
-  Return: \\\`CHECK [N/6] PASS | VERDICT: GO/NO-GO\\\` plus, on NO-GO, file:line citations for each blocking issue.\`
+  7. All TODO task labels use bare-number format ("1. xxx"), NOT "T1.", "Phase 1:", "Task-1." etc.
+     All Final Wave labels use bare-number format with "F" prefix: "F1. xxx", "F2. xxx", NOT "T-F1.", "F-1.", "Final-1." etc.
+  Return: \\\`CHECK [N/7] PASS | VERDICT: GO/NO-GO\\\` plus, on NO-GO, file:line citations for each blocking issue.\`
 )
 \`\`\`
 
@@ -201,6 +203,8 @@ Before presenting summary, verify:
 □ QA scenarios include BOTH happy-path AND negative/error scenarios?
 □ Zero acceptance criteria require human intervention?
 □ QA scenarios use specific selectors/data, not vague descriptions?
+□ All TODO labels use bare-number format ("1. ", "2. ")? NO T1./Phase 1:/Task-1. etc.
+□ All Final Wave labels use "F" + number format ("F1. ", "F2. ")? NO T-F1./F-1./Final-1. etc.
 \`\`\`
 
 ### Gap Handling Protocol
diff --git a/src/agents/prometheus/plan-template.ts b/src/agents/prometheus/plan-template.ts
index 452d62592..fe715e38d 100644
--- a/src/agents/prometheus/plan-template.ts
+++ b/src/agents/prometheus/plan-template.ts
@@ -163,6 +163,9 @@ Max Concurrent: 7 (Waves 1 & 2)
 > Implementation + Test = ONE Task. Never separate.
 > EVERY task MUST have: Recommended Agent Profile + Parallelization info + QA Scenarios.
 > **A task WITHOUT QA Scenarios is INCOMPLETE. No exceptions.**
+> **FORMAT**: Task labels MUST use bare numbers: \`1.\`, \`2.\`, \`3.\` — NOT \`T1.\`, \`Task 1.\`, \`Phase 1:\`.
+> The /start-work progress counter requires exact format. Deviation = progress shows 0/0.
+> Final Verification Wave labels MUST use \`F1.\`, \`F2.\`, etc. — NOT \`T-F1.\`, \`F-1.\`, \`Final 1.\`.
 
 - [ ] 1. [Task Title]
 
diff --git a/src/config/schema/hooks.ts b/src/config/schema/hooks.ts
index bdee70718..72a43722a 100644
--- a/src/config/schema/hooks.ts
+++ b/src/config/schema/hooks.ts
@@ -57,6 +57,7 @@ export const HookNameSchema = z.enum([
   "todo-description-override",
   "webfetch-redirect-guard",
   "fsync-skip-warning",
+  "plan-format-validator",
   "legacy-plugin-toast",
 ])
 
diff --git a/src/hooks/index.ts b/src/hooks/index.ts
index 3dc503077..493414d34 100644
--- a/src/hooks/index.ts
+++ b/src/hooks/index.ts
@@ -67,3 +67,4 @@ export { createWebFetchRedirectGuardHook } from "./webfetch-redirect-guard"
 export { createLegacyPluginToastHook } from "./legacy-plugin-toast"
 export { createFsyncSkipWarningHook } from "./fsync-skip-warning"
 export { createNotepadWriteGuardHook } from "./notepad-write-guard"
+export { createPlanFormatValidatorHook } from "./plan-format-validator"
diff --git a/src/hooks/plan-format-validator/hook.ts b/src/hooks/plan-format-validator/hook.ts
new file mode 100644
index 000000000..db708a870
--- /dev/null
+++ b/src/hooks/plan-format-validator/hook.ts
@@ -0,0 +1,134 @@
+import { existsSync, readFileSync } from "node:fs"
+import { resolve } from "node:path"
+
+import type { PluginInput } from "@opencode-ai/plugin"
+
+import { getPlanProgress } from "../../features/boulder-state/storage"
+import { log } from "../../shared/logger"
+
+const WRITE_TOOLS = new Set(["Write", "Edit", "write", "edit"])
+
+const CHECKBOX_PATTERN = /^[-*]\s*\[[ xX]\]/m
+
+const HEADING_SECOND_LEVEL = /^##\s+/
+const HEADING_TODOS = /^##\s+TODOs\b/i
+const HEADING_FINAL_WAVE = /^##\s+Final Verification Wave\b/i
+const TOPLEVEL_CHECKBOX = /^[-*]\s*\[[ xX]?\]/
+
+function countRawTopLevelCheckboxes(content: string): number {
+  const lines = content.split(/\r?\n/)
+  let section: "todo" | "final-wave" | "other" = "other"
+  let count = 0
+
+  for (const line of lines) {
+    if (HEADING_SECOND_LEVEL.test(line)) {
+      section = HEADING_TODOS.test(line)
+        ? "todo"
+        : HEADING_FINAL_WAVE.test(line)
+          ? "final-wave"
+          : "other"
+      continue
+    }
+
+    if (section === "other") continue
+    if (!TOPLEVEL_CHECKBOX.test(line)) continue
+
+    count++
+  }
+
+  return count
+}
+
+function buildWarning(rawCount: number, parsedCount: number): string {
+  const skipped = rawCount - parsedCount
+
+  if (parsedCount === 0) {
+    return [
+      "",
+      "<plan-format-warning>",
+      `Plan has **${rawCount} task checkbox(es)** but \`getPlanProgress()\` parsed **0**.`,
+      "This means `/start-work` will show **\"Progress: 0/0\"** for this plan.",
+      "",
+      "**Fix**: Every task checkbox under `## TODOs` MUST start with a bare number",
+      "followed by dot + space: `1.`, `2.`, `3.` — NOT `T1.`, `Phase 1:`, `Task-1.` etc.",
+      "Every Final Verification Wave checkbox MUST start with `F` + number:",
+      "`F1.`, `F2.` — NOT `T-F1.`, `F-1.`, `Final-1.` etc.",
+      "</plan-format-warning>",
+    ].join("\n")
+  }
+
+  return [
+    "",
+    "<plan-format-warning>",
+    `Plan has **${rawCount} task checkbox(es)** but \`getPlanProgress()\` only parsed **${parsedCount}**. `,
+    `**${skipped} task(s)** have malformed labels and will be SKIPPED by the progress counter.`,
+    `\`/start-work\` will show \"Progress: ${parsedCount} tasks\" — missing ${skipped} task(s).`,
+    "",
+    "**Fix**: Ensure every skipped task checkbox uses bare-number format:",
+    "  `## TODOs` → `1.`, `2.`, `3.` (NOT `T1.`, `Phase 1:`, `Task-1.`)",
+    "  `## Final Verification Wave` → `F1.`, `F2.`, `F3.` (NOT `T-F1.`, `F-1.`, `Final-1.`)",
+    "</plan-format-warning>",
+  ].join("\n")
+}
+
+function isPlanWrite(tool: string, args: Record<string, unknown>): string | null {
+  if (!WRITE_TOOLS.has(tool)) return null
+
+  const filePath = (args.filePath ?? args.path ?? args.file) as string | undefined
+  if (!filePath) return null
+
+  return filePath
+}
+
+function isPlanFilePath(filePath: string): boolean {
+  const normalized = filePath.toLowerCase().replace(/\\/g, "/")
+  return normalized.includes(".omo/plans/") && normalized.endsWith(".md")
+}
+
+/**
+ * Programmatic plan format validator.
+ *
+ * After any agent writes to a `.omo/plans/*.md` file, compares the
+ * raw top-level checkbox count against `getPlanProgress()` to detect
+ * malformed task labels. Warns the agent when some or all tasks
+ * will be skipped by the progress counter.
+ */
+export function createPlanFormatValidatorHook(_ctx: PluginInput) {
+  return {
+    "tool.execute.after": async (
+      input: { tool: string; sessionID: string; callID: string; args?: Record<string, unknown> },
+      output: { title: string; output: string; metadata: unknown },
+    ): Promise<void> => {
+      if (!input.args) return
+      if (typeof output.output !== "string") return
+      if (output.output.includes("<plan-format-warning>")) return
+
+      const filePath = isPlanWrite(input.tool, input.args)
+      if (!filePath) return
+      if (!isPlanFilePath(filePath)) return
+
+      const resolvedPath = resolve(_ctx.directory, filePath)
+      if (!existsSync(resolvedPath)) return
+
+      const content = readFileSync(resolvedPath, "utf-8")
+      if (!CHECKBOX_PATTERN.test(content)) return
+
+      const rawCount = countRawTopLevelCheckboxes(content)
+      if (rawCount === 0) return
+
+      const progress = getPlanProgress(resolvedPath)
+      const parsedCount = progress.total
+
+      if (rawCount === parsedCount) return
+
+      log(`[plan-format-validator] Plan ${filePath}: ${parsedCount}/${rawCount} tasks parsed`, {
+        sessionID: input.sessionID,
+        filePath,
+        rawCount,
+        parsedCount,
+      })
+
+      output.output = `${output.output}${buildWarning(rawCount, parsedCount)}`
+    },
+  }
+}
diff --git a/src/hooks/plan-format-validator/index.ts b/src/hooks/plan-format-validator/index.ts
new file mode 100644
index 000000000..0363ee2d8
--- /dev/null
+++ b/src/hooks/plan-format-validator/index.ts
@@ -0,0 +1 @@
+export { createPlanFormatValidatorHook } from "./hook"
diff --git a/src/plugin/hooks/create-tool-guard-hooks.ts b/src/plugin/hooks/create-tool-guard-hooks.ts
index d2f06146e..0ddfea118 100644
--- a/src/plugin/hooks/create-tool-guard-hooks.ts
+++ b/src/plugin/hooks/create-tool-guard-hooks.ts
@@ -20,6 +20,7 @@ import {
   createTeamToolGating,
   createFsyncSkipWarningHook,
   createNotepadWriteGuardHook,
+  createPlanFormatValidatorHook,
 } from "../../hooks"
 import {
   getOpenCodeVersion,
@@ -47,6 +48,7 @@ export type ToolGuardHooks = {
   fsyncSkipWarning: ReturnType<typeof createFsyncSkipWarningHook> | null
   teamToolGating: ReturnType<typeof createTeamToolGating> | null
   notepadWriteGuard: ReturnType<typeof createNotepadWriteGuardHook> | null
+  planFormatValidator: ReturnType<typeof createPlanFormatValidatorHook> | null
 }
 
 export function createToolGuardHooks(args: {
@@ -147,6 +149,10 @@ export function createToolGuardHooks(args: {
     ? safeHook("fsync-skip-warning", () => createFsyncSkipWarningHook())
     : null
 
+  const planFormatValidator = isHookEnabled("plan-format-validator")
+    ? safeHook("plan-format-validator", () => createPlanFormatValidatorHook(ctx))
+    : null
+
   const notepadWriteGuard = isHookEnabled("notepad-write-guard")
     ? safeHook("notepad-write-guard", () => createNotepadWriteGuardHook())
     : null
@@ -169,5 +175,6 @@ export function createToolGuardHooks(args: {
     fsyncSkipWarning,
     teamToolGating,
     notepadWriteGuard,
+    planFormatValidator,
   }
 }
diff --git a/src/plugin/tool-execute-after.ts b/src/plugin/tool-execute-after.ts
index 104cd6fd5..859bbb065 100644
--- a/src/plugin/tool-execute-after.ts
+++ b/src/plugin/tool-execute-after.ts
@@ -170,6 +170,7 @@ export function createToolExecuteAfterHandler(args: {
       await hooks.webfetchRedirectGuard?.["tool.execute.after"]?.(hookInput, output)
       await hooks.fsyncSkipWarning?.["tool.execute.after"]?.(hookInput, output)
       await hooks.jsonErrorRecovery?.["tool.execute.after"]?.(hookInput, output)
+      await hooks.planFormatValidator?.["tool.execute.after"]?.(hookInput, output)
     }
 
     if (input.tool === "extract" || input.tool === "discard") {