diff --git a/.claude-plugin/plugin.json b/.claude-plugin/plugin.json
index 7674b1f..2c247ad 100644
--- a/.claude-plugin/plugin.json
+++ b/.claude-plugin/plugin.json
@@ -1,6 +1,6 @@
 {
   "name": "cys",
-  "version": "0.6.21",
+  "version": "0.6.22",
   "description": "Development methodology skills with parallel plan execution: design, plan, run, check, ship. Named after the author's twin daughters, Cielo y Sophia.",
   "author": { "name": "Christian Bacilio" },
   "repository": "https://github.com/bacsystem/parallel-plan-executor",
diff --git a/.cursor-plugin/plugin.json b/.cursor-plugin/plugin.json
index 7a2820b..9f989ee 100644
--- a/.cursor-plugin/plugin.json
+++ b/.cursor-plugin/plugin.json
@@ -1,6 +1,6 @@
 {
   "name": "cys",
-  "version": "0.6.21",
+  "version": "0.6.22",
   "description": "Development methodology skills for design, plan, check, and ship — parallel plan execution (cys:run) is Claude Code only for now.",
   "author": { "name": "Christian Bacilio" },
   "repository": "https://github.com/bacsystem/parallel-plan-executor",
diff --git a/CHANGELOG.md b/CHANGELOG.md
index b01efb9..de5c73b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,31 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## 0.6.22 — 2026-07-22
+
+Fixed:
+
+- `src/plan-parser.js`: two diagnostic gaps found by an external review
+  with empirical reproduction (not static reading) — both let a
+  symbol-based dependency vanish from the plan's DAG without a useful
+  warning, so a task that should have been serialized could instead run
+  in parallel with its producer.
+  - A `- Consumes:`/`- Produces:` value with only a single-character
+    symbol between backticks (e.g. `` `x` ``) hit the anti-prose
+    `length > 1` filter and got the generic "no backtick-quoted symbols"
+    warning — false, the line has one. The warning now names the real
+    cause and cites the dropped symbol.
+  - A task missing the `**Interfaces:**` section entirely (typically a
+    header typo like `**Interface:**`) silently produced empty
+    `consumes`/`produces` with no warning at all — the single most
+    destructive parse miss and, until now, the only silent one. The
+    parser now warns and suggests writing `None` explicitly.
+
+  Neither fix changes the graph a well-formed plan produces — both only
+  make the diagnostics tell the truth. `skills/plan/SKILL.md` now also
+  documents that the `**Interfaces:**` header itself must always be
+  present.
+
 ## 0.6.21 — 2026-07-21
 
 Added:
diff --git a/gemini-extension.json b/gemini-extension.json
index 0c2ae1d..4457a1b 100644
--- a/gemini-extension.json
+++ b/gemini-extension.json
@@ -1,6 +1,6 @@
 {
   "name": "cys",
-  "version": "0.6.21",
+  "version": "0.6.22",
   "description": "Development methodology skills for design, plan, check, and ship — parallel plan execution (cys:run) is Claude Code only for now.",
   "repository": "https://github.com/bacsystem/parallel-plan-executor",
   "license": "MIT"
diff --git a/package.json b/package.json
index 8dde7c6..90acf7f 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "parallel-plan-executor",
-  "version": "0.6.21",
+  "version": "0.6.22",
   "author": "Christian Bacilio",
   "private": true,
   "type": "module",
diff --git a/skills/plan/SKILL.md b/skills/plan/SKILL.md
index 50045f5..91c6e88 100644
--- a/skills/plan/SKILL.md
+++ b/skills/plan/SKILL.md
@@ -62,7 +62,11 @@ Hard rules (the executor's parser depends on them):
 - **One entry per line** in Consumes/Produces — a value wrapping onto a
   second line is silently lost by the parser.
 - `Consumes: None` means an empty list; write it when a task is
-  independent.
+  independent. The `**Interfaces:**` header itself must always be present
+  — omitting it entirely (e.g. a typo like `**Interface:**`) silently
+  drops every symbol-based dependency for that task; the parser warns
+  when the header is missing, but write `None` explicitly rather than
+  relying on that warning.
 - Two tasks touching the same file are automatically serialized by the
   executor; design task boundaries so files are disjoint whenever
   possible — disjoint tasks run in parallel.
diff --git a/src/plan-parser.js b/src/plan-parser.js
index 26b01ca..01c77cb 100644
--- a/src/plan-parser.js
+++ b/src/plan-parser.js
@@ -40,6 +40,14 @@ function extractSection(body, sectionRe) {
   return match ? match[1] : '';
 }
 
+// A diferencia de extractSection (que aplana "sin match" y "match vacío" a ''), esta
+// devuelve null cuando la sección falta por completo, para que parseInterfaces pueda
+// distinguir "no hay sección" de "la sección está pero vacía".
+function extractOptionalSection(body, sectionRe) {
+  const match = body.match(sectionRe);
+  return match ? match[1] : null;
+}
+
 function parseFiles(body) {
   const section = extractSection(body, FILES_SECTION_RE);
   const files = { create: [], modify: [], test: [] };
@@ -67,6 +75,7 @@ const IDENTIFIER_RE = /[A-Za-z_][A-Za-z0-9_.]*/g;
 
 function extractSymbols(line) {
   const symbols = [];
+  const droppedShort = [];
   for (const [, rawSpan] of line.matchAll(BACKTICK_SPAN_RE)) {
     // Drop parenthesized call-argument lists first (e.g. the "name" in
     // `createWidget(name)`) so parameter names aren't mistaken for separate
@@ -80,16 +89,31 @@ function extractSymbols(line) {
     }
     for (const [identifier] of span.matchAll(IDENTIFIER_RE)) {
       if (identifier.length > 1) symbols.push(identifier);
+      else droppedShort.push(identifier);
     }
   }
-  return symbols;
+  return { symbols, droppedShort };
 }
 
 // "None"/"N/A"/"nothing" al comienzo del valor significa deliberadamente vacío.
 const NO_SYMBOLS_RE = /^(none|n\/a|nothing)\b/i;
 
 function parseInterfaces(body, taskId, warnings) {
-  const section = extractSection(body, INTERFACES_SECTION_RE);
+  const section = extractOptionalSection(body, INTERFACES_SECTION_RE);
+  if (section === null) {
+    // La sección entera falta — típicamente un typo en el header (**Interface:**,
+    // **Interfaz:**) o una tarea escrita a mano sin ella. Es el caso más destructivo
+    // (borra TODAS las dependencias por símbolo de la tarea) y era el único que no
+    // avisaba: un valor vacío sí warns, una línea sin backticks sí warns. Puede ser
+    // legítimo (tarea sin interfaces) — por eso es warning, no error, igual que el
+    // consumidor huérfano. Hallazgo de revisión externa 2026-07-22.
+    warnings.push(
+      `Task ${taskId}: no **Interfaces:** section found — symbol-based dependencies ` +
+      `for this task cannot be inferred; if the task has none, write ` +
+      `"- Consumes: None" / "- Produces: None" explicitly`
+    );
+    return { consumes: [], produces: [] };
+  }
   const lines = section.split('\n');
   const interfaces = { consumes: [], produces: [] };
   for (let i = 0; i < lines.length; i++) {
@@ -116,14 +140,26 @@ function parseInterfaces(body, taskId, warnings) {
       );
       continue;
     }
-    const symbols = extractSymbols(value);
+    const { symbols, droppedShort } = extractSymbols(value);
     if (symbols.length === 0) {
-      // La línea tiene contenido pero ningún backtick: se ignora, pero avisando — una
-      // dependencia perdida en silencio es justo lo que este parser debe evitar.
-      warnings.push(
-        `Task ${taskId}: ${consumes ? 'Consumes' : 'Produces'} line has no backtick-quoted ` +
-        `symbols and was ignored: "${value}"`
-      );
+      const kind = consumes ? 'Consumes' : 'Produces';
+      if (droppedShort.length > 0) {
+        // La causa real: había símbolos entre backticks, pero de 1 carácter — el
+        // filtro anti-prosa (length > 1) los descarta a propósito. Decir "no
+        // backtick-quoted symbols" mandaba a quien nombró su símbolo `x` a buscar
+        // el problema equivocado. Hallazgo de revisión externa 2026-07-22.
+        warnings.push(
+          `Task ${taskId}: ${kind} single-character symbol(s) ` +
+          `${droppedShort.map((s) => `\`${s}\``).join(', ')} were ignored ` +
+          `(too likely to be prose) — rename to 2+ characters if it's a real symbol: "${value}"`
+        );
+      } else {
+        // La línea tiene contenido pero ningún backtick: se ignora, pero avisando — una
+        // dependencia perdida en silencio es justo lo que este parser debe evitar.
+        warnings.push(
+          `Task ${taskId}: ${kind} line has no backtick-quoted symbols and was ignored: "${value}"`
+        );
+      }
       continue;
     }
     (consumes ? interfaces.consumes : interfaces.produces).push(...symbols);
diff --git a/tests/plan-parser.test.js b/tests/plan-parser.test.js
index fc5e046..242ee1b 100644
--- a/tests/plan-parser.test.js
+++ b/tests/plan-parser.test.js
@@ -180,6 +180,42 @@ test('una anotación bold con texto detrás NO termina la sección; un header so
     'la anotación inline no debe cortar la sección (b.js se perdía en silencio)');
 });
 
+test('una tarea sin sección **Interfaces:** genera un warning (hallazgo de revisión externa 2026-07-22: un typo en el header — p. ej. **Interface:** — borraba todas las dependencias por símbolo de la tarea sin un solo aviso, el único caso del parser que callaba)', () => {
+  const text = [
+    '### Task 1: Producer fine',
+    '',
+    '**Interfaces:**',
+    '- Produces: `foo`',
+    '',
+    '- [ ] **Step 1: x**',
+    '',
+    '### Task 2: Section missing entirely',
+    '',
+    '**Files:**',
+    '- Create: `b.js`',
+    '',
+    '- [ ] **Step 1: x**',
+  ].join('\n');
+  const { tasks, warnings } = parsePlanWithDiagnostics(text);
+  assert.deepEqual(tasks[1].interfaces, { consumes: [], produces: [] });
+  assert.equal(warnings.length, 1);
+  assert.match(warnings[0], /Task 2/);
+  assert.match(
+    warnings[0],
+    /no .*Interfaces:.*section/i,
+    'la ausencia total de la sección debe avisar — es el caso más destructivo y era el único silencioso'
+  );
+});
+
+test('el plan de ejemplo hello-parallel no gana warnings nuevos (regresión: es un plan bien formado)', () => {
+  const examplePlan = readFileSync(
+    path.join(here, '../examples/hello-parallel/plan.md'),
+    'utf8'
+  );
+  const { warnings } = parsePlanWithDiagnostics(examplePlan);
+  assert.deepEqual(warnings, []);
+});
+
 test('warns cuando una línea Consumes/Produces con contenido no tiene ningún backtick', () => {
   const text = [
     '### Task 1: A',
@@ -196,6 +232,27 @@ test('warns cuando una línea Consumes/Produces con contenido no tiene ningún b
   assert.match(warnings[0], /no backtick/);
 });
 
+test('un símbolo de 1 carácter se descarta con un warning que dice la causa REAL (hallazgo de revisión externa 2026-07-22: el warning genérico "no backtick-quoted symbols" mentía — la línea sí los tenía)', () => {
+  const text = [
+    '### Task 1: Uses short symbol',
+    '',
+    '**Interfaces:**',
+    '- Consumes: `x`',
+    '',
+    '- [ ] **Step 1: x**',
+  ].join('\n');
+  const { tasks, warnings } = parsePlanWithDiagnostics(text);
+  assert.deepEqual(tasks[0].interfaces.consumes, [], 'el filtro se mantiene: 1 char no es símbolo');
+  assert.equal(warnings.length, 1);
+  assert.match(warnings[0], /Task 1/);
+  assert.match(
+    warnings[0],
+    /single-character/i,
+    'el warning debe nombrar la causa real (símbolo de 1 carácter descartado), no "no backtick-quoted symbols"'
+  );
+  assert.match(warnings[0], /`x`/, 'debe citar el símbolo descartado para que sea encontrable');
+});
+
 test('no warnea por "None" ni por líneas correctamente backtickeadas', () => {
   const text = [
     '### Task 1: A',