Implements R7 + R8 of the Constitution alpha: launcher-composed operator
overlays so a user's *.local deltas reach the model as one pre-merged blob
(DESIGN §3.2), without re-injecting full base prose.
- composeContract(runtime, mosaicHome=MOSAIC_HOME): testable pure fn extracted
from the launcher prompt assembly; buildRuntimePrompt delegates to it.
- Overlay logic (deltas by value, base files keep residency):
- USER.local.md -> appended under the # User Profile block (USER is injected)
- SOUL.local.md + STANDARDS.local.md -> trailing # Operator Overlays section
(their bases are load-on-demand; only the small delta is injected, so the
P3 byte-budget tiering is preserved). Whitespace-only overlays ignored.
- Absent *.local -> base-only, automatically.
- New command: mosaic compose-contract <harness> -> prints the composed blob
to stdout (inspection / mosaic doctor / diffing / the composer test).
- defaults/AGENTS.md: bare-launch self-load fallback now nudges to relaunch via
mosaic <harness> (or mosaic doctor) when *.local overlays exist (R7 known-limit).
- compose-contract.spec.ts (7 tests): per-tier anchors, Tier-3 byte-equality
(injected L0 == CONSTITUTION.md on disk), overlay present/absent, per-harness.
ASSUMPTION: overlays injected as deltas-by-value under labeled sections; bases
keep existing residency. Rationale in docs/scratchpads/p5-overlay-composer.md.
Verified: 7 composer + 26 launch tests pass; tsc-clean on touched files;
prettier clean. Defers to P6: CONTRIBUTING.md + compliance matrix, line-count
CI ceiling, aiguide reconcile, alpha tag.
Refs #604, #542
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EsgTQzV5YUGk1JtCLP4B83
