[TomCC7]

A* accepts generated OccupancyGrid and returns generated Path without reconstructing source timestamps through floats. The existing Python search works on numeric cells; the existing compiled C++ extension uses the same boundary. Legacy callers retain legacy Path output while the remaining navigation consumers migrate. Both navigation-map strategies preserve generated metadata.

Parent: #4673. Project: https://linear.app/dimensional/project/message-encoding-refactor-05a3ddb4af3e/overview

Category	Files	Change
Planning boundary	1	Shared numeric search and generated/legacy path construction
Navigation costmaps	1	Retain input value identity through existing operations
Tests	1	Both actual backends, obstacle/unknown routes, origin rotation, exact metadata and ownership
CI	1	Installed-wheel provenance and focused checks

After installing this commit, run this offline example (defaults to the main wheel's compiled C++ A*):

import numpy as np
from dimos.messages.std_msgs.msg import Header
from dimos.msgs.occupancy import occupancy_from_array
from dimos.msgs.time import time_from_nanoseconds, to_nanoseconds
from dimos.navigation.go2.replanning_a_star.min_cost_astar import min_cost_astar

stamp = 1700000000123456789
costmap = occupancy_from_array(
    np.zeros((5, 5), dtype=np.int8), resolution=1.0,
    header=Header(frame_id="map", stamp=time_from_nanoseconds(stamp)),
)
path = min_cost_astar(costmap, goal=(4, 4), start=(0, 0))
assert path is not None
assert path.poses[-1].pose.position.x == 4
assert to_nanoseconds(path.header.stamp) == stamp

Validation: 20 focused source and 20 installed-wheel tests; 4 existing A* and 2 navigation-map golden regressions; strict typing of two production files; applicable hooks; normal main wheel build; full runtime pip check (198 packages). Exact snippet above passes against installed main wheel. Six project fixtures were SHA256/size verified before safe extraction. The legacy timed Python/C++ comparison test was deliberately not run under the benchmark pause. No performance, hardware or GitHub CI result is claimed. This layer does not yet migrate the GlobalPlanner/controller ports or remove legacy value types.