docs(dragoon): the 262144 ceiling, the 200,000 window, and the 95 % trigger law

Shape + harness contract on the endpoint page, AGENTS.md, and the OMP
Harness worked example recomputed to the live pair; the 400-zone law now
names the 85 %-comments vs 95 %-config disagreement as the recurring
cause and points at the seam that enforces the arithmetic.

AGENTS.md

@@ -419,16 +419,17 @@ disagrees with it is the bug.
   digest-pinned `ghcr.io/peonist-ai/halogen-flash-server@sha256:0c61bf84…`.
   Engine stdout (the boot ledger: weights, KV pool, clamp) goes to
   `/home/dank/logs/frank_dragoon.log`, NOT the journal.
-- Shape: `HALOGEN_CTX=200704` is the **per-request ceiling** (a longer prompt
-  is a 400, never a truncation); `HALOGEN_KV_SLOTS=2` over ONE
-  `HALOGEN_KV_POOL_POSITIONS=401408` pool — pool positions buy concurrency,
-  the per-request window never moves; `HALOGEN_SPEC_ADAPT=0` keeps the MTP
-  drafter always armed (the adaptive default disarms it and halves decode);
-  server sampler 1.0/0.95/20.
-- Harness contract: `models.yml` `contextWindow: 155648` = ceiling − 45,056.
-  The clamp is `min(45056, window − est − 4096)` and the chars/4 estimate
-  under-counts, so a harness window equal to the ceiling makes every long
-  request a guaranteed 400. Reasoning arrives in `reasoning_content`; the
+- Shape: `HALOGEN_CTX=262144` (the checkpoint's native window) is the
+  **per-request ceiling** (a longer prompt is a 400, never a truncation);
+  `HALOGEN_KV_SLOTS=2` over ONE `HALOGEN_KV_POOL_POSITIONS=401408` pool —
+  pool positions buy concurrency, the per-request window never moves;
+  `HALOGEN_SPEC_ADAPT=0` keeps the MTP drafter always armed (the adaptive
+  default disarms it and halves decode); server sampler 1.0/0.95/20.
+- Harness contract: `models.yml` `contextWindow: 200000` — ~45k+ under the
+  ceiling. The clamp is `min(45056, window − est − 4096)` and the chars/4
+  estimate under-counts (trigger is 95 %), so a harness window at the ceiling
+  makes every long request a guaranteed 400.
+  Reasoning arrives in `reasoning_content`; the
   template rejects `reasoning_effort` outside `xhigh|medium|low`; images are
   OpenAI `image_url` parts (probe ≥256 px); `response_format` unsupported;
   `/completion`, `/ping`, `/props`, `/tokenize` are 404.