REF-003: retire bash workflow dual path

[jmjava]

Summary

REF-003 removes the duplicate bash workflow, gate, pointer, and registry implementations so Python sdlc_engine is the only lifecycle flow. Bash keeps install/upgrade packaging and a few retained utilities, which are now thin Python-engine clients.

All six operations (T01–T06) are complete and every acceptance criterion was executed rather than inferred.

What changed

• Twin deleted. sdlc-workflow.sh, sdlc-team-registry.sh, and sdlc-pointer.sh are gone from templates/agent-context/ and sdlc-spdd/scripts/ — 3,100 shipped template LOC, 6,200 including the dogfood copies.
• One mandatory engine. scripts/sdlc.sh requires Python 3.12 and an importable sdlc_engine, with no bash fallback. SDLC_ENGINE=shell and SDLC_GATE_ENGINE=shell exit non-zero; SDLC_ENGINE=python stays accepted as a no-op.
• Retained utilities. start-agent-session.sh, capture-session-memory.sh, and accept-lessons.sh call the engine through SDLC_PY and no longer source a twin or shell out to bare python3 for engine behavior.
• Shell bridge. sdlc-engine shell resolves helpers in both orchestrator scripts/ and installed sdlc-spdd/scripts/ layouts.
• Packaging. Init and upgrade stop shipping the twins, upgrade backs up then deletes the exact retired paths, and install verification asserts their absence.
• Harness matrix. test-sdlc-workflow.sh, test-sdlc-pointer.sh, and test-archive-work.sh are replaced by engine/tests_unit/ coverage; their CI workflows are removed.
• Docs. Operator, testing, engine, template, and research docs describe one mandatory Python engine.

Defects found and fixed during review

1. Complexity gate. Extending cmd_shell for installed targets raised its CCN from 4 to 6, and the gate fails on any rise in a touched function. Candidate enumeration and lookup moved into _shell_script_candidates and _resolve_shell_script.
2. Harness Python resolution. Three migrated harnesses pinned ${REPO_ROOT}/.venv/bin/python, but CI installs the engine into the job interpreter and never creates a repo venv, so test-sdlc-workflow failed on a path that did not exist. Resolution now goes through one shared tests/lib/engine-python.sh, which test-integration-merge.sh and tests/live-consumer/lib.sh also use instead of their own copies of the same fallback chain.
3. Misleading version error. resolve_engine_python parsed the version with read -r major minor <<<"$(...)". When the interpreter could not run at all, the here-string still supplied one empty line, so read returned 0 and the guard printed is 3. with an empty minor — which is how defect 2 surfaced in CI. It now detects the empty version string and reports an unrunnable interpreter, and prints the full major.minor for a wrong version.

REASONS Canvas

• Work ID: REF-003-retire-bash-workflow-dual-path
• Canvas: sdlc-spdd/spdd/canvas/REF-003-retire-bash-workflow-dual-path.md
• Review: sdlc-spdd/spdd/reviews/REF-003-retire-bash-workflow-dual-path-review.md
• Sync: sdlc-spdd/spdd/sync/REF-003-retire-bash-workflow-dual-path-sync.md

Checklist

• Canvas updated or synced
• One operation per coding session respected
• Tests added or updated
• Review completed
• Safeguards respected
• CI gates pass
• If command/prompt adapter files changed, ran adapter parity validation

Test evidence

Check	Result
Suite 1 — unit	288 passed
Suite 2 — integration	151 passed, coverage 91.58% (gate 90%)
Research suite	87 passed
Shell harnesses	24/25 passed; test-guide-stack-live.sh skipped (needs a live Guide + Neo4j stack)
Live-consumer shell matrix	113 passed, 0 failed, 1 skipped
Installed-target smoke	45/45 install checks, plus claim/pointer/next/status/gate/capture/accept and the shell bridge
ShellCheck	bash -n clean; -S error clean
Complexity gate	PASS against origin/main
Canvas / requirements / adapter / diagram validators	PASS
Lifecycle gates (review, retro, sync)	PASS

Not covered

• test-guide-stack-live.sh needs a live Guide + Neo4j stack and was not run; it does not exercise the dispatcher contract this Work ID changed.
• Manual chat smoke was not performed. The command adapters changed only in generated prose (removing "even when SDLC_ENGINE=shell"), and adapter parity plus spec generation are green.