feat(ui): hillshade the deep rungs — form from light across slope (T-1213)

relief_q now reaches the renderer, and the first pass spent it on brightness:
lighten where the ground is high, darken where it is low. That moved the numbers
(District 13.72 -> 77.01 lum spread) and still looked like moss, because the eye
does not read landform from absolute brightness. It reads it from light falling
ACROSS a gradient — height-shading gives a rise and a fall the same tone, so no
ridge ever reads as a ridge.

So relief drives a proper hillshade: the local gradient of the field dotted with
a light from the upper-left. The light direction is not a free choice; lit from
the lower-right the brain inverts the read and valleys pop out as ridges.

THE SCALE IS MEASURED PER CANVAS, not fixed, and the first attempt at this failed
exactly the way this file already warned a fixed gradient constant would (see
RUGGEDNESS_BASELINE_CELLS: "the same 4-cell delta reads 21.86 at Region and 0.08
at District"). With a constant full-scale of 8:

    Region 81.72 but District 77.01 -> 20.01, Quarter 42.56 -> 16.44

because at District's 3.8 m per cell neighbouring cells barely differ. The
terrain layer now measures each canvas's own mean |gradient| once per rebuild and
the hillshade normalizes against it, so one constant works at every rung.

Ladder (tooling/atlas-flatness, lum p1-p99), flat -> shipped:

    Global    145.69 -> 145.69   unchanged; relief_q is flat 50 at orbital
    Region     33.59 ->  54.30
    District   13.72 ->  74.43
    Quarter    11.01 ->  73.72

District and Quarter now read as terrain — ridgelines, valleys, and the stipple
organised into contour-like bands. Judged by eye on the captures, not by the
metric alone.

Stipple full-scale 25 -> 60. The old value was calibrated against a relief_q that
never arrived, so it was tuned to the elev_q fallback; with the real plane nearly
every land cell earned a mark and Region read as static (17,599 distinct colours,
more than twice Global's, for a quarter of the legibility). Form comes from the
hillshade now; the stipple is grain on top of it.

REGION IS NOT FIXED, and the cause is T-1240 rather than this change. It renders
as fine uniform stucco: a Region cell is 379 m of ground while the relief field's
content sits in the 128-1024 m band, so the field is at or below Nyquist and the
gradient the hillshade reads is aliasing, not slope. min_wl_m defaults to 0 on
the served path, so nothing truncates the octaves Region cannot resolve — which
is precisely what T-1240 proposes to fix. That ticket said the stale cutoff was
"currently inert"; it is now the thing capping Region, and T-1240 is updated
with the measurement.

Three tests, on direction rather than magnitude so tuning does not rewrite them:
a hill's west flank lit and east flank shadowed, a uniform field shading nothing,
and the canvas edge not drawing a rim. That last one is a bug this nearly
shipped: `_l8_value` returns 0 out of bounds and 0 on relief_q means MAXIMUM
HOLLOW, so sampling off-canvas posts a full-scale false gradient all the way
round the frame. The sample position is clamped instead.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.pql/changelog/ticket_history/2026-08.sql

@@ -634,3 +634,30 @@ was missing, because each asserted a field it already knew about and none
 asserted the SET. There is now a test that walks all eight dense planes of
 EncodedStepCanvas and fails if any is absent from the decode — verified by
 disabling the fix and watching it fail by name.', NULL, '2026-08-16 13:05:35', '2026-08-16 13:05:35.162', '2026-08-16 13:05:35.162', NULL, 'fc36ad2f1acb58e73b53d53ac6402a95', 2) ON CONFLICT(hash) DO NOTHING;
+INSERT INTO ticket_history (ticket_record_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('06FXRSY7QWD8J5X6G1N86WMKEC', 'description', 'Found during T-1213 (2026-08-07). MIN_WL_BANDS_M (layer_proxy.rs) is built from 2*DISTRICT_M (4,096 m) and 2*QUARTER_M (1,024 m) -- Nyquist for a sample spacing equal to the rung''s CELL SIZE. That was correct while a rung fixed SPACING; after D-255''s extent inversion a rung fixes EXTENT and District''s spacing is 2048/540 = 3.8 m, so its true Nyquist floor is ~7.6 m. The bands are off by roughly the canvas cell count (~540x). This is the same class of defect as the Global 2x1 wire-extent sentinel the D-258 amendment documents: a constant that was correct under the pre-inversion model and silently outlived it. The code even states the consequence as though intended -- district_profile.rs''s comment reads ''At District''s real Nyquist floor (4,096 m) every VOXEL_OCTAVE_WAVELENGTHS_M entry is truncated, so relief is always exactly 0.0 there''. IMPORTANT SCOPE NOTE, verified before filing: this is currently INERT for the step canvas. step_canvas_viewer._fire_request() calls request_now(body, rung, center, extent) with no min_wl_m, so it defaults to 0, and quantize_min_wl_m(0) returns 0 (the leading sentinel band) -- no truncation happens on the served path. It therefore only affects the legacy layer_proxy district-window consumer. It is NOT the cause of the flat District/Quarter rungs; that is elev_q''s 80 m quantisation (0-100 across MAX_REGION_ELEVATION_KM = 8.0 km), measured at d1 mean 0.02 with the cutoff already disabled. Fix: derive the cutoff from the resolved canvas spacing rather than the rung cell size. Check the layer_proxy consumer''s expectations first -- MIN_WL_BANDS_M is shared, carries a const assert tying band 4 to OCTAVE_WAVELENGTHS_M[3], and is part of the cache key, so a change there is not local.', 'Found during T-1213 (2026-08-07). MIN_WL_BANDS_M (layer_proxy.rs) is built from 2*DISTRICT_M (4,096 m) and 2*QUARTER_M (1,024 m) -- Nyquist for a sample spacing equal to the rung''s CELL SIZE. That was correct while a rung fixed SPACING; after D-255''s extent inversion a rung fixes EXTENT and District''s spacing is 2048/540 = 3.8 m, so its true Nyquist floor is ~7.6 m. The bands are off by roughly the canvas cell count (~540x). This is the same class of defect as the Global 2x1 wire-extent sentinel the D-258 amendment documents: a constant that was correct under the pre-inversion model and silently outlived it. The code even states the consequence as though intended -- district_profile.rs''s comment reads ''At District''s real Nyquist floor (4,096 m) every VOXEL_OCTAVE_WAVELENGTHS_M entry is truncated, so relief is always exactly 0.0 there''. IMPORTANT SCOPE NOTE, verified before filing: this is currently INERT for the step canvas. step_canvas_viewer._fire_request() calls request_now(body, rung, center, extent) with no min_wl_m, so it defaults to 0, and quantize_min_wl_m(0) returns 0 (the leading sentinel band) -- no truncation happens on the served path. It therefore only affects the legacy layer_proxy district-window consumer. It is NOT the cause of the flat District/Quarter rungs; that is elev_q''s 80 m quantisation (0-100 across MAX_REGION_ELEVATION_KM = 8.0 km), measured at d1 mean 0.02 with the cutoff already disabled. Fix: derive the cutoff from the resolved canvas spacing rather than the rung cell size. Check the layer_proxy consumer''s expectations first -- MIN_WL_BANDS_M is shared, carries a const assert tying band 4 to OCTAVE_WAVELENGTHS_M[3], and is part of the cache key, so a change there is not local.
+
+---
+NO LONGER INERT IN CONSEQUENCE (2026-08-16, found via T-1213). This ticket''s own
+scope note says the stale cutoff "is NOT the cause of the flat District/Quarter
+rungs". That was correct, and it is now the cause of something else: it caps
+REGION.
+
+With relief_q reaching the renderer (T-1213 fixed a missing protocol decode) and
+driving a hillshade, Region renders as a fine uniform stucco — texture at the
+pixel scale, no landform. District and Quarter, on the same code, read as real
+terrain (lum p1-p99 74.43 and 73.72 against Region''s 54.30).
+
+The reason is sampling, and it is this ticket: a Region cell is 379 m of ground,
+while the relief field''s own content sits in the 128-1024 m composition band plus
+192 m inclusions. The field is at or below Nyquist for that sampling, so every
+neighbouring cell differs by an essentially independent draw and the gradient the
+hillshade reads is ALIASING rather than slope. Because min_wl_m defaults to 0 on
+the served path, nothing truncates the octaves Region cannot resolve — which is
+precisely the fix this ticket proposes ("derive the cutoff from the resolved
+canvas spacing rather than the rung cell size").
+
+So the visible symptom to fix against is now concrete: Region should show the
+same kind of ridge-and-valley form District does, at its own scale, and it will
+once the octaves below its sampling resolution are cut. The T-1213 work made this
+observable; before it, relief_q never arrived and the rung was flat for a
+different reason entirely.', NULL, '2026-08-16 16:23:17', '2026-08-16 16:23:17.190', '2026-08-16 16:23:17.190', NULL, '42875477f1917d72cd064d584df2b11f', 2) ON CONFLICT(hash) DO NOTHING;

.pql/changelog/tickets/2026-08.sql

@@ -611,3 +611,30 @@ asserted the SET. There is now a test that walks all eight dense planes of
 EncodedStepCanvas and fails if any is absent from the decode — verified by
 disabling the fix and watching it fail by name.', 'in_progress', 'high', NULL, NULL, 'D-258', '2026-07-26 21:54:15.245', '2026-08-16 13:05:35.162', NULL, 'e611e465ff1fd8de7b71b3de10702fec', 2) ON CONFLICT(record_id) DO UPDATE SET type=excluded.type, parent_record_id=excluded.parent_record_id, title=excluded.title, description=excluded.description, status=excluded.status, priority=excluded.priority, assigned_to=excluded.assigned_to, team=excluded.team, decision_ref=excluded.decision_ref, updated_at=excluded.updated_at, deleted_at=excluded.deleted_at, hash=excluded.hash, canonical_version=excluded.canonical_version WHERE excluded.updated_at >= tickets.updated_at;
 INSERT INTO tickets (record_id, type, parent_record_id, title, description, status, priority, assigned_to, team, decision_ref, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('06G0P0F9C3RKKK23ZHHTANCPZW', 'bug', '06FBPPMZNNEV052DBYYY3A897C', 'test_visibility_texture_update_performance flakes under gate load — min-of-7 was not enough', 'Wall-clock perf assertion in client/tests/test_fog_shader.gd:213 (best-of-7 < 0.5 ms, D-059 budget) failed the pre-push gate on 2026-08-16 at 0.606 ms, then passed 23/23 in isolation minutes later on the same build. The failing run was a full-suite pass inside the hook, which runs AFTER the tooling suite and cargo checks, so every one of the seven samples was inflated together by a loaded machine. My manual full-suite run of the identical tree passed 1830/0. Nothing in the pushed change touches the fog path (Atlas protocol decode, colorize, terrain layer, tooling). This is the SECOND recorded hardening cycle for the same failure mode: the estimator is already min-of-7 (T-1210) after median-of-5 flaked three times on 2026-07-26 when a cargo build saturated the cores (0.549/0.503/0.638). Taking the minimum defends against ONE slow sample, not against sustained saturation, which is precisely the condition the gate creates by design. Direction: measure CPU time rather than wall clock (Time.get_ticks_usec measures elapsed, so it prices the scheduler in), or make the budget assertion load-aware, or move the perf assertions out of the correctness gate into a dedicated bench run where the machine is quiet. Do NOT simply raise the 0.5 threshold -- that discards the budget D-059 set without deciding to.', 'backlog', 'medium', NULL, 'client', NULL, '2026-08-16 14:37:49.792', '2026-08-16 14:37:49.792', NULL, '513d27f28c0ff1a50bd36692fb96fa46', 2) ON CONFLICT(record_id) DO UPDATE SET type=excluded.type, parent_record_id=excluded.parent_record_id, title=excluded.title, description=excluded.description, status=excluded.status, priority=excluded.priority, assigned_to=excluded.assigned_to, team=excluded.team, decision_ref=excluded.decision_ref, updated_at=excluded.updated_at, deleted_at=excluded.deleted_at, hash=excluded.hash, canonical_version=excluded.canonical_version WHERE excluded.updated_at >= tickets.updated_at;
+INSERT INTO tickets (record_id, type, parent_record_id, title, description, status, priority, assigned_to, team, decision_ref, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('06FXRSY7QWD8J5X6G1N86WMKEC', 'task', '06FB0TNSRZXCHGS16BFHSSGSV4', 'MIN_WL_BANDS_M octave cutoffs are pre-extent-inversion (stale, currently inert)', 'Found during T-1213 (2026-08-07). MIN_WL_BANDS_M (layer_proxy.rs) is built from 2*DISTRICT_M (4,096 m) and 2*QUARTER_M (1,024 m) -- Nyquist for a sample spacing equal to the rung''s CELL SIZE. That was correct while a rung fixed SPACING; after D-255''s extent inversion a rung fixes EXTENT and District''s spacing is 2048/540 = 3.8 m, so its true Nyquist floor is ~7.6 m. The bands are off by roughly the canvas cell count (~540x). This is the same class of defect as the Global 2x1 wire-extent sentinel the D-258 amendment documents: a constant that was correct under the pre-inversion model and silently outlived it. The code even states the consequence as though intended -- district_profile.rs''s comment reads ''At District''s real Nyquist floor (4,096 m) every VOXEL_OCTAVE_WAVELENGTHS_M entry is truncated, so relief is always exactly 0.0 there''. IMPORTANT SCOPE NOTE, verified before filing: this is currently INERT for the step canvas. step_canvas_viewer._fire_request() calls request_now(body, rung, center, extent) with no min_wl_m, so it defaults to 0, and quantize_min_wl_m(0) returns 0 (the leading sentinel band) -- no truncation happens on the served path. It therefore only affects the legacy layer_proxy district-window consumer. It is NOT the cause of the flat District/Quarter rungs; that is elev_q''s 80 m quantisation (0-100 across MAX_REGION_ELEVATION_KM = 8.0 km), measured at d1 mean 0.02 with the cutoff already disabled. Fix: derive the cutoff from the resolved canvas spacing rather than the rung cell size. Check the layer_proxy consumer''s expectations first -- MIN_WL_BANDS_M is shared, carries a const assert tying band 4 to OCTAVE_WAVELENGTHS_M[3], and is part of the cache key, so a change there is not local.
+
+---
+NO LONGER INERT IN CONSEQUENCE (2026-08-16, found via T-1213). This ticket''s own
+scope note says the stale cutoff "is NOT the cause of the flat District/Quarter
+rungs". That was correct, and it is now the cause of something else: it caps
+REGION.
+
+With relief_q reaching the renderer (T-1213 fixed a missing protocol decode) and
+driving a hillshade, Region renders as a fine uniform stucco — texture at the
+pixel scale, no landform. District and Quarter, on the same code, read as real
+terrain (lum p1-p99 74.43 and 73.72 against Region''s 54.30).
+
+The reason is sampling, and it is this ticket: a Region cell is 379 m of ground,
+while the relief field''s own content sits in the 128-1024 m composition band plus
+192 m inclusions. The field is at or below Nyquist for that sampling, so every
+neighbouring cell differs by an essentially independent draw and the gradient the
+hillshade reads is ALIASING rather than slope. Because min_wl_m defaults to 0 on
+the served path, nothing truncates the octaves Region cannot resolve — which is
+precisely the fix this ticket proposes ("derive the cutoff from the resolved
+canvas spacing rather than the rung cell size").
+
+So the visible symptom to fix against is now concrete: Region should show the
+same kind of ridge-and-valley form District does, at its own scale, and it will
+once the octaves below its sampling resolution are cut. The T-1213 work made this
+observable; before it, relief_q never arrived and the rung was flat for a
+different reason entirely.', 'backlog', 'medium', NULL, 'server', 'D-255', '2026-08-07 13:26:56.703', '2026-08-16 16:23:17.190', NULL, '1ed56273a1d81dbb6d0e1614598f744b', 2) ON CONFLICT(record_id) DO UPDATE SET type=excluded.type, parent_record_id=excluded.parent_record_id, title=excluded.title, description=excluded.description, status=excluded.status, priority=excluded.priority, assigned_to=excluded.assigned_to, team=excluded.team, decision_ref=excluded.decision_ref, updated_at=excluded.updated_at, deleted_at=excluded.deleted_at, hash=excluded.hash, canonical_version=excluded.canonical_version WHERE excluded.updated_at >= tickets.updated_at;