#3538 [Engine] Model rewrites slash-separated dates to dash-separated format after echo input — suspected IQ3_S quantization precision issue]: Model rewrites slash-separated dates to dash-separated format after echo input — suspected IQ3_S quantization precision issue

本文

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**Issue title**: `[Bug]: Model rewrites slash-separated dates to dash-separated format after echo input — suspected IQ3_S quantization precision issue`

**Strata version**: `0.1.41`

**What happened**

On the `strata` engine (`Niko1221/Strata`, v0.1.41) running Qwen3.8-Flash-Next (IQ3_S quantization), I tested whether the model preserves date formatting with a shell-style input:

Input:
```
echo "2026/10/21"
```

Expected the model to preserve the slash format (`2026/10/21`), but it replied:
```
2026-10-21
```

The model automatically changed the date separator from `/` to `-`. This caused a real problem when I asked it to download a file: the download URL contained a date path with slashes, and when the model called the download tool it rewrote the date in the arguments to dash format, so the download request pointed at the wrong URL.

Reproduces almost 100% of the time, not intermittent. Wondering whether other users have hit the same behavior, and whether it's related to IQ3_S quantization precision.

**Environment**

- Strata version: `0.1.41`
- Strata engine path: `/data/env/strata/Strata/engine/strata`
- Model: `Qwen3.8-Flash-Next-GSQ-RCO-IQ3_S` (two-shard GGUF, IQ3_S quantization)
- Config: `--max-context 262144`, `--kv int8`, `--spec 4`, `--spec-min-p 0.5`, `--resident-experts`, `--vision`, `--pool-workers 15`
- Env vars: `STRATA_ADAPT_LAG=2`, `STRATA_EXCHANGE_ROTATE=1`, `STRATA_PF_FUSED=1`
- GPU: dual card (`gpu: [0, 1]`), `parallel: 4`
- Full config JSON attached below

**Steps to reproduce**

1. Start the strata engine (v0.1.41) with the config above.
2. Send the model: `echo "2026/10/21"`
3. Observe output: the model returns `2026-10-21` instead of preserving `2026/10/21`.
4. In a tool-calling scenario, if the model is asked to build a URL containing `2026/10/21` and call the download tool, it rewrites the date in the arguments to `2026-10-21`, causing the download to fail.

**Additional info**

- I suspect this is related to precision loss from IQ3_S quantization, but I'm not sure whether it's a tokenizer-level deviation in handling digits/symbols or model behavior degradation at this quantization level.
- If it would help to compare against a non-quantized version, or if you need the engine log (`strata-iq3_s.log`), let me know.
- I don't currently have the setup to test whether this also occurs at other quantization levels (e.g. Q4, Q5) or BF16 — would appreciate confirmation from anyone who can.

**Full environment config**

```json
{
 "exe": "/data/env/strata/Strata/engine/strata",
 "args": [
  "--pack", "/data/env/strata/Strata-data/packs/iq3_s",
  "--native", "/data/env/strata/Strata-data/models/IQ3_S/Qwen3.8-Flash-Next-GSQ-RCO-IQ3_S-00001-of-00002.gguf",
  "--ple-gguf", "/data/env/strata/Strata-data/models/IQ3_S/Qwen3.8-Flash-Next-GSQ-RCO-IQ3_S-00002-of-00002.gguf",
  "--expert-profile", "/data/env/strata/Strata/data/expert-profile.bin",
  "--expert-cache", "auto",
  "--prefill", "auto",
  "--spec", "4",
  "--spec-min-p", "0.5",
  "--mtp", "/data/env/strata/Strata-data/mtp/rt",
  "--max-context", "262144",
  "--kv", "int8",
  "--resident-experts",
  "--vision",
  "--pool-workers", "15"
 ],
 "cwd": "/data/env/strata/Strata",
 "tokenizer": "/data/env/strata/Strata-data/packs/iq3_s/tokenizer",
 "model_name": "qwen3-coder",
 "env": {
  "STRATA_ADAPT_LAG": "2",
  "STRATA_EXCHANGE_ROTATE": "1",
  "STRATA_PF_FUSED": "1"
 },
 "gpu": [0, 1],
 "parallel": 4,
 "host": "172.16.0.1",
 "port": 8000
}
```