Battam1111/Myco

v0.7.1 — 2026-04-30 — myco.mcp shim revival (v0.7.0 hotfix)

Zero R1-R7 surface deltas; zero new manifest verbs; zero new lint dims; zero subsystem changes; schema v2 unchanged. This is a hotfix that reverts v0.7.0's src/myco/mcp/ shim deletion after the deletion broke the substrate's own owner-Claude-Desktop config within 2 hours of release.

Incident

v0.7.0 shipped at 2026-04-29T16:45Z with the myco.mcp back-compat shim deleted under the assumption that 4 versions of DeprecationWarning (v0.6.13 → v0.6.16) had migrated all downstream consumers. Within ~2 hours the substrate's own owner-Claude-Desktop MCP host raised:

C:\Python313\python.exe: No module named myco.mcp
[error] Server disconnected

Owner's claude_desktop_config.json had "args": ["-m", "myco.mcp"] — the legacy path. The deprecation warnings emitted to stderr were never read by the host UI or the owner across 4 versions of notice. The shim deletion cascaded into immediate substrate inoperability for the owner's Claude Desktop instance.

Root cause

The v0.7.0 craft's "load-bearing assumption" stated: "Internal codebase has zero from myco.mcp consumers (verified pre-execution); only external downstream substrates importing the legacy path are affected, and they were already being warned via DeprecationWarning since v0.6.13."

The hidden flaw: the substrate has no telemetry surface to verify "external" consumer count. The deletion was executed against a claim ("no downstream consumer") that was unverifiable. It should have been classified P0 BLOCK rather than load-bearing assumption.

What changed

Group A — Shim restoration

• src/myco/mcp/__init__.py (75 LoC, recovered via git show 7c4e7d5~1:src/myco/mcp/__init__.py). Updated docstring §"Scheduled removal" from "no earlier than v0.7.0" to "indefinite, gated on SH3 telemetry or v1.0.0 stable freeze" with the v0.7.0 incident named in the body.
• src/myco/mcp/__main__.py (22 LoC, same recovery path).
• tests/unit/boundary/test_legacy_mcp_shim.py (133 LoC, 5 tests verifying import resolution + re-export integrity + boot + warning emission).
• Stderr deprecation copy updated to name the v0.7.0 incident.

Group B — Owner-config migration (out-of-band, not committed)

• %APPDATA%/Claude/claude_desktop_config.json updated: args=["-m", "myco.mcp"] → args=["-m", "myco.boundary.mcp"]. The owner's substrate now boots via the canonical path; the shim continues to serve any other downstream consumer with a still-stale legacy config.

New substrate doctrine (deferred for L2 amendment)

A public-API deletion discipline is now load-bearing. From v0.7.1+, a shim deletion candidate must satisfy ONE of:

• (a) Internal-only verification — grep returns zero hits across src/, tests/, scripts/, examples/ AND the path is NOT exposed via any CLI or MCP host entry point AND no plugin manifest declares the path.
• (b) Telemetry verification — substrate has run for N senesce cycles with a shim-hit counter (introduced by SH3 dim, future) showing zero hits.

v0.7.0 satisfied (a) only for internal imports. It missed "exposed via plugin host config." That gap produced the regression. This discipline lands in docs/architecture/L2_DOCTRINE/boundary.md § "Legacy import shims" as a craft-driven amendment in a follow-up doc-only molt; the v0.7.1 hotfix does not amend L2 to keep the hotfix path tight.

Break from v0.7.0

REVERSAL of v0.7.0's sole public API break. from myco.mcp import build_server, main works again at v0.7.1 — same shape it had at v0.6.16. Downstream substrates whose host configs still spell python -m myco.mcp continue to operate (with a louder stderr deprecation pointer). The "removed at v0.7.0" claim in the v0.7.0 contract_changelog is superseded by this entry's "removal indefinite, gated on telemetry."

No other backward-compat impact. v0.7.0's other deletions (legacy_v0_3, dist stale wheels, unused assets, dead digestion modules, test consolidation, doc archives) are ALL preserved. v0.7.1 reverses ONLY the src/myco/mcp/ shim deletion + restores its test.

What did NOT change

• All 7 R-rules: identical text.
• All 7 subsystems: identical doctrine.
• All 46 lint dimensions: identical roster, severities, fixability.
• All 20 verbs: identical manifest, CLI, MCP shape.
• v0.7.0's structural compaction (15 MB / 388 files deleted, 11.5K LoC archived, 4 fail-silent dim fixes): all preserved.
• Schema v2 shape: unchanged.

Pre-flight gate verification

• ruff check src tests scripts — clean
• ruff format --check src tests scripts — 297 files formatted
• mypy src/myco — 148 source files, no issues
• pytest -q — 1532 passed, 1 skipped (up from v0.7.0 baseline of 1525, +7 from restored shim test suite)
• myco immune — exit 0 baseline preserved
• python -m myco.mcp --help — boots successfully (legacy invocation works)
• python -m myco.boundary.mcp --help — boots successfully (canonical invocation works)
• scripts/verify_mcp_boot.py — 20 tools, handshake green

Governing craft: docs/primordia/v0_7_1_shim_revival_craft_2026-04-30.md.
Predecessor: v0.7.0 (Major Autolysis), shipped 2026-04-29.