fix(devops,contracts): resolve issues #1543-#1546 (deploy.sh errexit, Redis docs, contract tests)

[anifast-123]

Summary

Resolves four third-wave audit issues spanning DevOps, docs, and contract test coverage.

#1546 — deploy.sh custom deploy/init error messages were dead code under set -e

scripts/deploy.sh captured command output via VAR=$(cmd) and then checked if [[ $? -ne 0 ]]. Under set -e, a failing command substitution in a plain assignment terminates the script before that check, so the custom diagnostics were unreachable.

Fix: check the exit status in the same statement — if ! DEPLOY_OUTPUT=$(...); then — for both stellar contract deploy and stellar contract invoke.

Verification: with mocked cargo/stellar, the old script exits 7 and prints no custom message; the new script exits 1 and prints Error: Deployment failed (or Error: Contract initialization failed) plus the captured command output. This is the errexit control-flow bug specifically, distinct from the already-closed #887 (env-var defaults) and #515 (deploy.sh vs deploy.ts divergence).

#1545 — docs told contributors docker compose up -d redis with no Redis service

docker-compose.yml does define a redis service, but its explanatory comment was attached to the pgbouncer service and backend/.env.example left REDIS_URL empty/unreachable.

Fix: restore the Redis comment, give pgbouncer its own, and pin/document REDIS_URL=redis://localhost:6379 — the port the redis compose service publishes — so the documented SSE-fanout flow works from a fresh clone. docker compose up -d redis targets a real, healthy service.

#1544 — Test cancel_stream/withdraw when sender == recipient

Added test_withdraw_self_stream_credits_shared_address_once and test_cancel_self_stream_settles_both_transfers: the shared address is credited exactly once on withdraw, and the two cancel_stream transfers (accrued to recipient + refund to sender) sum to the full deposit with no loss or duplication.

#1543 — Test cancel_stream on a fully accrued but never-withdrawn stream

Added test_cancel_fully_accrued_stream_without_withdraw_is_cancelled: the recipient receives 100% of the deposit, the sender refund is 0, and stream.status == StreamStatus::Cancelled (never Completed, which only apply_withdrawal sets).

Files changed

• scripts/deploy.sh — errexit-safe deploy/init error handling ([DevOps] deploy.sh's custom deploy/init error messages are dead code under set -e #1546)
• docker-compose.yml, docs/DEVELOPMENT.md, backend/.env.example — Redis service/URL consistency ([DevOps] docs/DEVELOPMENT.md tells contributors to docker compose up -d redis but no redis service exists #1545)
• contracts/stream_contract/src/test.rs — 3 new tests ([Contracts] Test cancel_stream on a fully accrued but never-withdrawn stream #1543, [Contracts] Test cancel_stream/withdraw when sender equals recipient #1544)

Testing

• cargo test -p stream_contract — 252 passed, 0 failed, 1 ignored (includes the 3 new tests)
• bash scripts/lint-rust.sh — cargo fmt --check + cargo clippy --all-targets -- -D warnings clean
• Mocked deploy.sh failure simulation for both the deploy and initialize paths (old vs new)
• docker compose config validates with the redis service present

closes #1543
closes #1544
closes #1545
closes #1546