diff --git a/README.md b/README.md
index 4af2667..03cbce1 100644
--- a/README.md
+++ b/README.md
@@ -110,6 +110,21 @@ sets the RAM budget and context immediately; the VRAM tier is enabled only when
 the current `glm` binary is linked with CUDA. Explicit flags and environment
 variables keep precedence over automatic values.
 
+Before loading the model, `coli doctor` performs a read-only readiness check and
+explains whether the selected Disk/RAM/VRAM placement is runnable:
+
+```bash
+COLI_MODEL=/nvme/glm52_i4 ./coli doctor
+COLI_MODEL=/nvme/glm52_i4 ./coli doctor --gpu 0 --ram 128 --json
+```
+
+Doctor validates the model directory, config, tokenizer, safetensors headers,
+engine executable, available RAM, requested NVIDIA devices, CUDA linkage, and the
+same placement budget used by `coli plan`. It never starts `glm`, reads tensor
+payloads, imports a model framework, or creates a CUDA context. The versioned JSON
+report uses stable check IDs for automation. Warnings keep exit status 0; missing
+requirements or an unsafe RAM projection return 1, while invalid CLI values return 2.
+
 The engine at runtime is pure C — python is only used by the one-time converter.
 
 ### Windows 11 (native, no WSL)
diff --git a/c/coli b/c/coli
index 32a80dc..f9e601e 100755
--- a/c/coli
+++ b/c/coli
@@ -8,6 +8,7 @@ CLI per far girare GLM-5.2 (744B) in locale, su CPU, in ~15-26 GB di RAM.
   coli run "prompt"         generazione singola
   coli info                 stato: modello, RAM, disco, config
   coli plan                 piano risorse Disk / RAM / VRAM
+  coli doctor               diagnosi installazione e piano di esecuzione
   coli bench [task...]      benchmark di qualità (MMLU/HellaSwag/...)
   coli convert              converte GLM-5.2-FP8 -> int4 (streaming)
   coli build                compila il motore
@@ -334,6 +335,23 @@ def cmd_plan(a):
     print(textwrap.indent(format_plan(plan),"  "))
     print()
 
+def cmd_doctor(a):
+    from doctor import exit_code, format_doctor, run_doctor
+    try:
+        ram,ctx,devices,vram=resource_request(a,os.environ)
+        if ctx<1: raise ValueError("--ctx deve essere positivo")
+        if ram<0: raise ValueError("--ram non puo essere negativo")
+        if vram<0: raise ValueError("--vram non puo essere negativo")
+    except ValueError as error:
+        report={"schema_version":1,"status":"error","model":os.path.abspath(a.model),
+                "checks":[{"id":"config.arguments","status":"fail","summary":str(error)}],
+                "plan":None}
+        print(json.dumps(report,indent=2) if a.json else format_doctor(report))
+        return 2
+    report=run_doctor(a.model,ram,ctx,devices,vram,engine_path=GLM)
+    print(json.dumps(report,indent=2) if a.json else format_doctor(report))
+    return exit_code(report)
+
 def cmd_run(a):
     need_model(a.model)
     prompt=" ".join(a.prompt) if a.prompt else sys.exit('uso: coli run "il tuo prompt"')
@@ -507,6 +525,8 @@ def main():
     sub.add_parser("build", parents=[common]); sub.add_parser("info", parents=[common])
     pp=sub.add_parser("plan",parents=[common])
     pp.add_argument("--json",action="store_true")
+    pd=sub.add_parser("doctor",parents=[common])
+    pd.add_argument("--json",action="store_true",help="emette un report JSON versionato")
     pr=sub.add_parser("run", parents=[common]);  pr.add_argument("prompt", nargs="*")
     sub.add_parser("chat", parents=[common])
     ps=sub.add_parser("serve", parents=[common])
@@ -523,8 +543,11 @@ def main():
     pc.add_argument("--ebits",type=int,default=4); pc.add_argument("--io-bits",type=int,default=8); pc.add_argument("--xbits",type=int,default=0)
     pc.add_argument("--no-mtp",action="store_true",help="salta la testa MTP (niente draft speculativi)")
     a=ap.parse_args()
-    {"build":cmd_build,"info":cmd_info,"plan":cmd_plan,"run":cmd_run,"chat":cmd_chat,"serve":cmd_serve,"bench":cmd_bench,
-     "convert":cmd_convert}.get(a.cmd, lambda _:(banner(),print(__doc__)))(a)
+    handler={"build":cmd_build,"info":cmd_info,"plan":cmd_plan,"doctor":cmd_doctor,
+             "run":cmd_run,"chat":cmd_chat,"serve":cmd_serve,"bench":cmd_bench,
+             "convert":cmd_convert}.get(a.cmd)
+    if handler: sys.exit(handler(a) or 0)
+    banner(); print(__doc__)
 
 if __name__=="__main__":
     signal.signal(signal.SIGINT, signal.default_int_handler)
diff --git a/c/doctor.py b/c/doctor.py
new file mode 100644
index 0000000..0fb74af
--- /dev/null
+++ b/c/doctor.py
@@ -0,0 +1,150 @@
+#!/usr/bin/env python3
+"""Read-only installation diagnostics for colibri."""
+
+import os
+import json
+import subprocess
+from pathlib import Path
+
+from resource_plan import GB, build_plan, discover_gpus, format_plan, memory_available
+
+
+def _check(identifier, status, summary, **details):
+    item = {"id": identifier, "status": status, "summary": summary}
+    if details:
+        item["details"] = details
+    return item
+
+
+def cuda_linkage(engine_path):
+    """Return CUDA linkage state without loading the executable or CUDA runtime."""
+    if not Path(engine_path).is_file() or os.name != "posix":
+        return {"linked": False, "missing": False}
+    try:
+        result = subprocess.run(["ldd", str(engine_path)], capture_output=True, text=True,
+                                timeout=3, check=False)
+    except (OSError, subprocess.SubprocessError):
+        return {"linked": False, "missing": False}
+    lines = [line for line in result.stdout.splitlines() if "libcudart" in line]
+    return {"linked": any("not found" not in line for line in lines),
+            "missing": any("not found" in line for line in lines)}
+
+
+def run_doctor(model, ram_gb=0, context=4096, gpu_indices=None, vram_gb=0, *,
+               engine_path, available_memory=None, available_disk=None, gpus=None,
+               linkage=None):
+    """Collect a complete report. No model payload, engine, or CUDA context is loaded."""
+    model = Path(model).expanduser().resolve()
+    checks = []
+    plan = None
+
+    if model.is_dir() and os.access(model, os.R_OK):
+        checks.append(_check("model.path", "pass", "model directory is readable", path=str(model)))
+    elif model.is_dir():
+        checks.append(_check("model.path", "fail", "model directory is not readable", path=str(model)))
+    else:
+        checks.append(_check("model.path", "fail", "model directory does not exist", path=str(model)))
+
+    config = model / "config.json"
+    try:
+        valid_config = isinstance(json.loads(config.read_text()), dict)
+    except (OSError, ValueError):
+        valid_config = False
+    checks.append(_check("model.config", "pass" if valid_config else "fail",
+                         "config.json is valid" if valid_config else "config.json is missing or invalid"))
+    tokenizer = model / "tokenizer.json"
+    checks.append(_check("model.tokenizer", "pass" if tokenizer.is_file() else "fail",
+                         "tokenizer.json found" if tokenizer.is_file() else "tokenizer.json is missing"))
+    if model.is_dir() and os.access(model, os.W_OK):
+        checks.append(_check("storage.persistence", "pass", "model directory can store usage and KV state"))
+    elif model.is_dir():
+        checks.append(_check("storage.persistence", "warn", "model directory is read-only; disable persistence or change permissions"))
+    else:
+        checks.append(_check("storage.persistence", "skip", "persistence requires a model directory"))
+
+    engine = Path(engine_path)
+    if engine.is_file() and os.access(engine, os.X_OK):
+        checks.append(_check("engine.binary", "pass", "engine executable is ready", path=str(engine)))
+    elif engine.is_file():
+        checks.append(_check("engine.binary", "fail", "engine exists but is not executable", path=str(engine)))
+    else:
+        checks.append(_check("engine.binary", "fail", "engine is not built", path=str(engine)))
+
+    available_memory = memory_available() if available_memory is None else available_memory
+    detected_gpus = discover_gpus() if gpus is None else list(gpus)
+    linkage = cuda_linkage(engine) if linkage is None else linkage
+    selected_gpus = detected_gpus
+    if gpu_indices is not None:
+        wanted = set(gpu_indices)
+        selected_gpus = [gpu for gpu in detected_gpus if gpu["index"] in wanted]
+
+    if gpu_indices == []:
+        checks.append(_check("accelerator.cuda", "skip", "GPU use was explicitly disabled"))
+    elif gpu_indices is not None and len(selected_gpus) != len(set(gpu_indices)):
+        checks.append(_check("accelerator.cuda", "fail", "one or more requested GPUs were not detected",
+                             requested=gpu_indices, detected=[gpu["index"] for gpu in detected_gpus]))
+    elif selected_gpus and linkage.get("missing"):
+        checks.append(_check("accelerator.cuda", "fail", "CUDA runtime library is missing"))
+    elif selected_gpus and linkage.get("linked"):
+        checks.append(_check("accelerator.cuda", "pass", "CUDA engine and devices are available",
+                             devices=[gpu["index"] for gpu in selected_gpus]))
+    elif selected_gpus:
+        checks.append(_check("accelerator.cuda", "warn", "NVIDIA GPU detected but the engine is CPU-only",
+                             devices=[gpu["index"] for gpu in selected_gpus]))
+    else:
+        checks.append(_check("accelerator.cuda", "skip", "no NVIDIA GPU detected; CPU path is available"))
+
+    try:
+        plan = build_plan(model, ram_gb, context, gpu_indices, vram_gb,
+                          available_memory=available_memory, available_disk=available_disk,
+                          gpus=detected_gpus)
+        model_info = plan["model"]
+        checks.append(_check("model.shards", "pass", "safetensors headers are valid",
+                             shards=model_info["shards"], model_bytes=model_info["model_bytes"]))
+        disk = plan["tiers"]["disk"]
+        disk_status = "warn" if disk["available_bytes"] < GB else "pass"
+        disk_summary = ("less than 1 GB is free for runtime state" if disk_status == "warn" else
+                        "model backing store is available")
+        checks.append(_check("storage.disk", disk_status, disk_summary,
+                             available_bytes=disk["available_bytes"], model_bytes=disk["model_bytes"]))
+        ram = plan["tiers"]["ram"]
+        if not available_memory:
+            ram_status, ram_summary = "warn", "available RAM could not be measured"
+        elif ram["budget_bytes"] > available_memory:
+            ram_status, ram_summary = "fail", "planned RAM budget exceeds available memory"
+        elif ram["cache_slots_per_layer"] < 1:
+            ram_status, ram_summary = "fail", "RAM budget cannot hold one expert slot per sparse layer"
+        else:
+            ram_status, ram_summary = "pass", "RAM budget is viable"
+        checks.append(_check("memory.ram", ram_status, ram_summary,
+                             available_bytes=available_memory, budget_bytes=ram["budget_bytes"],
+                             cache_slots_per_layer=ram["cache_slots_per_layer"]))
+        if plan["warnings"]:
+            checks.append(_check("placement.plan", "warn", "; ".join(plan["warnings"])))
+        else:
+            checks.append(_check("placement.plan", "pass", "tier placement has no warnings"))
+    except (OSError, ValueError, KeyError) as error:
+        checks.append(_check("model.shards", "fail", str(error)))
+        checks.append(_check("storage.disk", "skip", "storage check requires a valid model"))
+        checks.append(_check("memory.ram", "skip", "RAM projection requires a valid model"))
+        checks.append(_check("placement.plan", "skip", "placement requires a valid model"))
+
+    statuses = {item["status"] for item in checks}
+    status = "error" if "fail" in statuses else "warning" if "warn" in statuses else "ok"
+    return {"schema_version": 1, "status": status, "model": str(model),
+            "checks": checks, "plan": plan}
+
+
+def format_doctor(report):
+    icons = {"pass": "ok", "warn": "warn", "fail": "fail", "skip": "skip"}
+    lines = [f"colibri doctor · {report['model']}"]
+    for check in report["checks"]:
+        lines.append(f"[{icons[check['status']]:>4}] {check['id']:<18} {check['summary']}")
+    if report["plan"]:
+        lines.extend(["", format_plan(report["plan"])])
+    lines.extend(["", f"result {report['status']}"])
+    return "\n".join(lines)
+
+
+def exit_code(report):
+    return 1 if report["status"] == "error" else 0
diff --git a/c/tests/test_doctor.py b/c/tests/test_doctor.py
new file mode 100644
index 0000000..c618636
--- /dev/null
+++ b/c/tests/test_doctor.py
@@ -0,0 +1,167 @@
+import json
+import struct
+import subprocess
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+from doctor import exit_code, format_doctor, run_doctor
+from resource_plan import GB
+
+
+def write_shard(path, tensors):
+    offset = 0
+    header = {}
+    payload = b""
+    for name, size in tensors:
+        header[name] = {"dtype": "U8", "shape": [size],
+                        "data_offsets": [offset, offset + size]}
+        payload += b"\0" * size
+        offset += size
+    raw = json.dumps(header).encode()
+    path.write_bytes(struct.pack("<Q", len(raw)) + raw + payload)
+
+
+class DoctorTest(unittest.TestCase):
+    def setUp(self):
+        self.tmp = tempfile.TemporaryDirectory()
+        self.root = Path(self.tmp.name)
+        self.model = self.root / "model"
+        self.model.mkdir()
+        (self.model / "config.json").write_text(json.dumps({
+            "num_hidden_layers": 2,
+            "n_routed_experts": 2,
+            "kv_lora_rank": 4,
+            "qk_rope_head_dim": 2,
+            "qk_nope_head_dim": 3,
+            "v_head_dim": 5,
+            "num_attention_heads": 2,
+        }))
+        (self.model / "tokenizer.json").write_text("{}")
+        write_shard(self.model / "model.safetensors", [
+            ("model.embed_tokens.weight", 100),
+            ("model.layers.0.self_attn.q_a_proj.weight", 200),
+            ("model.layers.1.mlp.experts.0.gate_proj.weight", 30),
+            ("model.layers.1.mlp.experts.0.up_proj.weight", 30),
+            ("model.layers.1.mlp.experts.1.gate_proj.weight", 30),
+            ("model.layers.1.mlp.experts.1.up_proj.weight", 30),
+        ])
+        self.engine = self.root / "glm"
+        self.engine.write_text("#!/bin/sh\nexit 0\n")
+        self.engine.chmod(0o755)
+
+    def tearDown(self):
+        self.tmp.cleanup()
+
+    def report(self, **overrides):
+        arguments = {
+            "model": self.model,
+            "ram_gb": 16,
+            "context": 32,
+            "gpu_indices": [],
+            "vram_gb": 0,
+            "engine_path": self.engine,
+            "available_memory": 32 * GB,
+            "available_disk": 100 * GB,
+            "gpus": [],
+            "linkage": {"linked": False, "missing": False},
+        }
+        arguments.update(overrides)
+        return run_doctor(**arguments)
+
+    @staticmethod
+    def checks_by_id(report):
+        return {check["id"]: check for check in report["checks"]}
+
+    def test_healthy_cpu_install_has_versioned_report(self):
+        report = self.report()
+        checks = self.checks_by_id(report)
+
+        self.assertEqual(report["schema_version"], 1)
+        self.assertEqual(report["status"], "ok")
+        self.assertIsNotNone(report["plan"])
+        self.assertEqual(checks["accelerator.cuda"]["status"], "skip")
+        self.assertEqual(checks["memory.ram"]["status"], "pass")
+        self.assertEqual(checks["model.shards"]["details"]["shards"], 1)
+        self.assertEqual(exit_code(report), 0)
+
+    def test_missing_model_collects_failures_instead_of_stopping_early(self):
+        report = self.report(model=self.root / "missing")
+        checks = self.checks_by_id(report)
+
+        self.assertEqual(report["status"], "error")
+        self.assertEqual(checks["model.path"]["status"], "fail")
+        self.assertEqual(checks["model.config"]["status"], "fail")
+        self.assertEqual(checks["model.tokenizer"]["status"], "fail")
+        self.assertEqual(checks["model.shards"]["status"], "fail")
+        self.assertEqual(checks["storage.disk"]["status"], "skip")
+        self.assertIsNone(report["plan"])
+        self.assertEqual(exit_code(report), 1)
+
+    def test_non_executable_engine_and_excessive_ram_budget_fail(self):
+        self.engine.chmod(0o644)
+        report = self.report(ram_gb=40)
+        checks = self.checks_by_id(report)
+
+        self.assertEqual(checks["engine.binary"]["status"], "fail")
+        self.assertEqual(checks["memory.ram"]["status"], "fail")
+        self.assertEqual(report["status"], "error")
+
+    def test_requested_missing_gpu_is_a_failure(self):
+        report = self.report(gpu_indices=[1])
+        check = self.checks_by_id(report)["accelerator.cuda"]
+
+        self.assertEqual(check["status"], "fail")
+        self.assertEqual(check["details"], {"requested": [1], "detected": []})
+        self.assertEqual(exit_code(report), 1)
+
+    def test_cpu_engine_with_detected_gpu_is_only_a_warning(self):
+        gpu = {"index": 0, "name": "fixture", "total_bytes": 12 * GB,
+               "free_bytes": 10 * GB}
+        report = self.report(gpu_indices=None, gpus=[gpu])
+        check = self.checks_by_id(report)["accelerator.cuda"]
+
+        self.assertEqual(check["status"], "warn")
+        self.assertEqual(report["status"], "warning")
+        self.assertEqual(exit_code(report), 0)
+
+    def test_missing_cuda_runtime_is_a_failure(self):
+        gpu = {"index": 0, "name": "fixture", "total_bytes": 12 * GB,
+               "free_bytes": 10 * GB}
+        report = self.report(gpu_indices=[0], gpus=[gpu],
+                             linkage={"linked": False, "missing": True})
+
+        self.assertEqual(
+            self.checks_by_id(report)["accelerator.cuda"]["summary"],
+            "CUDA runtime library is missing",
+        )
+        self.assertEqual(report["status"], "error")
+
+    def test_text_format_contains_checks_plan_and_result(self):
+        output = format_doctor(self.report())
+
+        self.assertIn("model.path", output)
+        self.assertIn("disk   backing store", output)
+        self.assertTrue(output.endswith("result ok"))
+
+    def test_cli_json_is_machine_readable_without_loading_model(self):
+        cli = Path(__file__).parents[1] / "coli"
+        run = subprocess.run([
+            sys.executable, str(cli), "doctor", "--model", str(self.model),
+            "--gpu", "none", "--ram", "16", "--ctx", "32", "--json",
+        ], text=True, capture_output=True, check=False)
+
+        # The repository engine may be absent; doctor must still return one complete JSON report.
+        self.assertIn(run.returncode, (0, 1))
+        report = json.loads(run.stdout)
+        self.assertEqual(report["schema_version"], 1)
+        self.assertEqual(Path(report["model"]), self.model.resolve())
+        self.assertIn(report["status"], ("ok", "warning", "error"))
+        self.assertNotIn("\033", run.stdout)
+        self.assertTrue(run.stdout.lstrip().startswith("{"))
+        self.assertTrue(run.stdout.rstrip().endswith("}"))
+
+
+if __name__ == "__main__":
+    unittest.main()