diff --git a/dev/issues/README.md b/dev/issues/README.md
index 93b3bea..c4747fb 100644
--- a/dev/issues/README.md
+++ b/dev/issues/README.md
@@ -41,5 +41,5 @@ afectados y notas de implementacion.
 | 28  | Desacoplar launcher del registro    | [0028-decouple-launcher.md](completed/0028-decouple-launcher.md)               | completado |
 | 29  | Tests para runtime y config         | [0029-core-tests.md](0029-core-tests.md)                                       | pendiente  |
 | 30  | Separacion Robot vs Agente          | [0030-robot-vs-agent.md](0030-robot-vs-agent.md)                               | pendiente  |
-| 31  | Expandir tools/file/                | [0031-expand-file-tools.md](0031-expand-file-tools.md)                         | pendiente  |
+| 31  | Expandir file tools (write, list, append, delete) | [0031-expand-file-tools.md](completed/0031-expand-file-tools.md)     | completado |
 | 32  | E2E: verificar skill /create-agent  | [0032-e2e-create-agent-skill.md](0032-e2e-create-agent-skill.md)               | pendiente  |
diff --git a/dev/issues/completed/0031-expand-file-tools.md b/dev/issues/completed/0031-expand-file-tools.md
new file mode 100644
index 0000000..b6a0145
--- /dev/null
+++ b/dev/issues/completed/0031-expand-file-tools.md
@@ -0,0 +1,32 @@
+# 0031 — Expandir tools/file/ con write, list, append, delete
+
+## Objetivo
+
+Ampliar el paquete `tools/file/` con operaciones de escritura, listado, append y borrado. Mantener el patron deny-by-default, validacion de symlinks, y respetar el flag `read_only` del config.
+
+## Estado: completado
+
+Implementado en rama `issue/0031-expand-file-tools`.
+
+### Archivos creados/modificados
+
+- `tools/file/validate.go` — NEW: validatePath(), validateWritePath(), resolveReal() extraidos de file.go
+- `tools/file/write.go` — NEW: write_file tool (crea/sobreescribe, MkdirAll, limite 1MB)
+- `tools/file/list.go` — NEW: list_directory tool (plano/recursivo, limite 500 entries)
+- `tools/file/append.go` — NEW: append_file tool (append o crear, limite 10MB total)
+- `tools/file/delete.go` — NEW: delete_file tool (solo archivos, nunca directorios)
+- `tools/file/file.go` — refactored: removidas funciones movidas a validate.go
+- `tools/file/write_test.go` — NEW: 11 tests
+- `tools/file/list_test.go` — NEW: 9 tests
+- `tools/file/append_test.go` — NEW: 11 tests
+- `tools/file/delete_test.go` — NEW: 9 tests
+- `agents/runtime.go` — registro condicional de las 4 tools nuevas
+
+### Seguridad
+
+- Deny-by-default en todas las tools (AllowedPaths vacio = todo denegado)
+- ReadOnly gate: write/append/delete solo se registran si ReadOnly == false
+- Path traversal protegido via resolveReal() + prefix validation
+- Symlink escape protegido via EvalSymlinks
+- Solo archivos en delete (nunca directorios)
+- Limites de tamano: 1MB write, 10MB append total, 64KB read output, 500 entries list