Fog of war reveals the ground around the bot through rock (t17)

Also: board rule to write tasks from chat in our own words, task
descriptions rewritten that way, and a note on lost web-board descriptions.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/agent-log.md

@@ -4,6 +4,19 @@ What agents have done, newest first. Add an entry for every piece of work: the d
 note or request it was for, what changed, the files touched, the tests run, and anything left
 open or not verified. Keep each entry short; the git history has the details.
 
+## 2026-10-24: t17 Fog of war reveals the ground around the bot (Claude Code, Codex)
+
+- `src/sim/fog.js`: `FOG_SENSE = 20`; `fogLook` also reveals every fog cell within 20 grains,
+  through rock (full to 16, fading to 20). Claude rewrote Codex's per-grain `Math.hypot` loop to
+  work per fog cell. `fogLook` cost: 0.042 → 0.043 ms (every 4 ticks).
+- `test/t_fog.js`: rock 12 grains away is seen, near the edge partly, 25 away still hidden.
+- `docs/systems/fog.md`, DESIGN.md decision. Also: `.kandown/kandown_work.md` rule to write
+  tasks from chat in our own words (no owner labels, dates or quotes); t16/t19 descriptions
+  rewritten that way; `docs/kandown.md` notes that web-board descriptions were lost.
+- Tests: `run_all.py --browser` all pass (220 `play.py` checks). `t_smooth` half-resolution failed
+  on two runs while the machine was loaded (load 6–10) and passed on the final run; timing
+  `fogLook` showed the change is not the cause. Screenshot `shots/fog-sense.png` checked.
+
 ## 2026-10-24: t19 Vacuum blow all visual (Claude Code, Codex)
 
 - The owner's description was lost in kandown; chosen in chat: bag rows light up and the card