配置没写的滤波键等于"关"，不再回落到会滤波的默认值 - What: DEFAULT_FORCE_MEDIAN_WINDOW 3 -> 1、DEFAULT_FLOW_EMA_ALPHA 0.5 -> 1.0（DEFAULT_FORCE_LOWPASS_HZ 本就是 0.0），并把注释改成"配置文件没写的键就是关，而不是我们觉得合理的那一档"——原因写在注释里：否则设备会去滤一个没人要求滤的测量，而文件里没有任何线索；实测的延迟/降噪数据保留在注释中，作为 balanced/low_noise 预设的依据。docs/filters.md 第 2 节增加"缺省 = 关"这一条并说明没有 filters 段的配置什么都不滤，预设表里 balanced 的用途由"默认建议"改为"建议起步档"（它不再是默认值）。examples/filters/README.md 补一句"整段删掉等价于 off"。tests/test_filter_presets.py 新增 test_a_config_with_no_filters_block_filters_nothing：把 box bundle 的 filters 段整段删掉后构造真实 Sensor，断言 filters_state() 报 ema 1.0 / median 1 / cutoff 0.0 且 any_stage_applied 为 False。 - Why: 上一版只把"非法值"改成回落到关，但"键根本不写"仍会走 DEFAULT_* 从而把 EMA 0.5 + 中值 3 打开——这与"配置自描述、文件说什么就跑什么、出厂默认全关"矛盾，且现实里存在大量没有 filters 段的手写配置（例如 _perf/cfg_res_280x300.json），它们会在无人察觉的情况下继续滤波。缺省开是这条链上最后一个隐藏默认值。 - Verification: 删掉 filters 段后实测 filters_state() = (1.0, 1, 0.0) 且 any_stage_applied=False，出厂 box/mini/finger 三份同样为全关；pytest tests/test_filter_presets.py + tests/test_calibration.py → 33 passed；SDK 全量 336 passed / 15 skipped（唯一失败仍是需要 1200 帧而样例只有 577 帧的 longrun 测试）；app 侧 studio 85 项与 shared 142 项测试、ui_check 554 项检查在升级后的 0.5.2 下全绿。 - Not in this change: 出厂 bundle 的三个显式值未动（本来就全关）；_perf 的两个校验脚本不在仓库内，已就地补上显式 filters 段（balanced）以保持"开 vs 关"对照仍有意义；app 侧 wrapper/齿轮/CSV 17 列未动。

src/orisys/sensor.py

@@ -32,16 +32,24 @@ from .signal_processing import (
 )
 
 # Default signal-conditioning settings (config: top-level "filters" block).
-# Measured on dd02-0703 at 280x300 (see the noise analysis in the perf notes):
-# flow EMA 0.5 + median 3 costs ~2 frames at 30 fps, cuts steady-press force
-# jitter by roughly half and removes ~85% of the heavy-tailed spikes, while also
-# stabilising vnormal/contact (which a force-level filter cannot do).
-# The force low-pass is OFF by default: on top of the EMA it added no measurable
-# noise benefit at the same latency, so it is kept as an opt-in stage for sites
-# with different noise characteristics.
+#
+# A key a config does not state is **off**, not "whatever we thought was
+# sensible": the file has to name what runs, or a device can be filtering a
+# measurement nobody asked it to filter and no reader of the file could tell.
+# The shipped bundles state all three values explicitly, so they are unaffected
+# by these defaults; a config with no "filters" block at all filters nothing.
+#
+# Which settings are worth asking for is measured, not guessed. On dd02-0703 at
+# 280x300 (see the noise analysis in the perf notes) flow EMA 0.5 + median 3
+# costs ~2 frames at 30 fps and cuts steady-press force jitter by roughly half
+# while also stabilising vnormal/contact (which a force-level filter cannot do);
+# that combination is the "balanced" preset. The force low-pass stays off there
+# too: on top of the EMA it added no measurable noise benefit at the same
+# latency, so it is an opt-in stage for sites with different noise
+# characteristics (the "low_noise" preset).
 DEFAULT_FORCE_LOWPASS_HZ = 0.0
-DEFAULT_FORCE_MEDIAN_WINDOW = 3
-DEFAULT_FLOW_EMA_ALPHA = 0.5
+DEFAULT_FORCE_MEDIAN_WINDOW = 1
+DEFAULT_FLOW_EMA_ALPHA = 1.0
 
 #: Named filter presets, so a recommendation is *executable* instead of a
 #: comment in a JSON file (``json.load`` cannot carry comments). A config may