BC5 readiness: cross-language wire-replay decoders

.gitignore

@@ -6,6 +6,7 @@ spec/build/
 
 # Conformance test runner artifacts
 conformance/runner/go/conformance-runner
+conformance/runner/go/go
 conformance/runner/ruby/Gemfile.lock
 conformance/runner/typescript/node_modules/
 
@@ -37,7 +38,11 @@ python/dist/
 python/.pytest_cache/
 python/.coverage
 python/src/*.egg-info/
+
+# Python conformance runner artifacts
 conformance/runner/python/.venv/
+conformance/runner/python/**/__pycache__/
+conformance/runner/python/**/*.pyc
 conformance/runner/python/uv.lock
 
 # TypeScript SDK build artifacts

CONTRIBUTING.md

@@ -293,7 +293,76 @@ gate refuses to run if any fixture operation lacks a dispatch.
 Because live canary fixtures live in the shared `conformance/tests/` directory,
 offline conformance runners must treat `mode` as part of the shared schema and
 execute only mock tests: omitted `mode` or `mode: "mock"`. `mode: "live"` entries
-belong to the TypeScript live wire-capture runner until replay runners are added.
+belong to the TypeScript live wire-capture runner and the cross-language
+wire-replay runners described next.
+
+### Wire replay (cross-language)
+
+The TypeScript live runner is the single canonical wire-capturer. When invoked
+with `LIVE_RECORD_DIR=<path>`, it persists every captured response to
+`<path>/<backend>/wire/<test>.json` with the snapshot format
+`{ operation, pages: [{status, headers, body, bodyText, url}], pages_count }`.
+
+The Ruby, Python, Go, and Kotlin runners each have a *wire-replay mode* that
+reads those snapshots and decodes each page through their SDK. No HTTP calls,
+no mock servers — the input is the canonical wire bytes captured by the TS
+runner. Decode results land at
+`<path>/<backend>/decode/<language>/<test>.json` with the format
+`{ schema_version, operation, pages: [{decoded, decode_error, missing_required, extras_seen}] }`.
+
+Each runner enforces three coverage gates at startup before doing any decode
+work:
+
+1. **Decoder coverage** — every operation in `live-my-surface.json` has a
+   decode case in this runner.
+2. **Snapshot completeness** — every operation in `live-my-surface.json` has
+   a corresponding snapshot file at `<path>/<backend>/wire/`.
+3. **Snapshot recognition** — every snapshot's `operation` field is in
+   `live-my-surface.json` (catches drift between TS dispatch and the shared
+   fixture).
+
+Each gate prints which operations triggered it so the operator can fix the
+right side: TS dispatch, the fixture, or the replay runner.
+
+Two-stage flow:
+
+```bash
+# Step 1: TS captures canonical wire snapshots (live HTTP, requires creds).
+BASECAMP_LIVE=1 \
+BASECAMP_TOKEN=<token> \
+BASECAMP_ACCOUNT_ID=<account> \
+BASECAMP_BACKEND=bc4 \
+LIVE_RECORD_DIR=tmp/canary \
+make conformance-typescript-live
+
+# Step 2: each language replays those snapshots through its SDK (offline).
+for lang in ruby python go kotlin; do
+  WIRE_REPLAY_DIR=tmp/canary BASECAMP_BACKEND=bc4 \
+    make conformance-$lang-replay
+done
+```
+
+Step 2 needs no credentials and no network — it's pure decode + walk. The
+extras-observed output across languages is a consistency check on the
+hand-rolled schema walkers (which mirror the TS validator's required + extras
+algorithm in each language). Any per-language divergence in `extras_seen`
+points at a walker bug in the diverging language.
+
+`make conformance-typescript-live` is owned by PR 2; the four
+`make conformance-*-replay` targets ship in PR 3. The orchestrating
+`make conformance-live` and `make check-bc5-compat` targets that thread
+TS capture → replay → BC4↔BC5 comparison together land in PR 4.
+
+When the SDK gains a new operation in `live-my-surface.json`, it must be
+added to:
+
+- `conformance/runner/typescript/live-dispatch.ts` — TS dispatch case.
+- `conformance/runner/ruby/replay-runner.rb` — Ruby decoder.
+- `conformance/runner/python/replay_runner.py` — Python decoder.
+- `conformance/runner/go/replay_runner.go` — Go decoder.
+- `kotlin/conformance/src/main/kotlin/com/basecamp/sdk/conformance/ReplayRunner.kt` — Kotlin decoder.
+
+Each runner's coverage gate refuses to start until all five are in place.
 
 ## API gap registry (`spec/api-gaps/`)
 

Makefile

@@ -370,7 +370,7 @@ py-clean:
 # Conformance Test targets
 #------------------------------------------------------------------------------
 
-.PHONY: conformance conformance-go conformance-kotlin conformance-typescript conformance-typescript-live conformance-ruby conformance-python conformance-build
+.PHONY: conformance conformance-go conformance-go-replay conformance-kotlin conformance-kotlin-replay conformance-typescript conformance-typescript-live conformance-ruby conformance-ruby-replay conformance-python conformance-python-replay conformance-build
 
 # Build conformance test runner
 conformance-build:
@@ -382,11 +382,27 @@ conformance-go: conformance-build
 	@echo "==> Running Go conformance tests..."
 	cd conformance/runner/go && ./conformance-runner
 
+# Run Go wire-replay against snapshots written by the TS live runner.
+# Required env: WIRE_REPLAY_DIR, BASECAMP_BACKEND. Opt-in: not in `make check`.
+conformance-go-replay:
+	@echo "==> Running Go wire-replay runner..."
+	@test -n "$$WIRE_REPLAY_DIR" || (echo "WIRE_REPLAY_DIR is required" >&2; exit 1)
+	@test -n "$$BASECAMP_BACKEND" || (echo "BASECAMP_BACKEND is required" >&2; exit 1)
+	cd conformance/runner/go && go run .
+
 # Run Kotlin conformance tests
 conformance-kotlin:
 	@echo "==> Running Kotlin conformance tests..."
 	cd kotlin && ./gradlew :conformance:run
 
+# Run Kotlin wire-replay against snapshots written by the TS live runner.
+# Required env: WIRE_REPLAY_DIR, BASECAMP_BACKEND. Opt-in: not in `make check`.
+conformance-kotlin-replay:
+	@echo "==> Running Kotlin wire-replay runner..."
+	@test -n "$$WIRE_REPLAY_DIR" || (echo "WIRE_REPLAY_DIR is required" >&2; exit 1)
+	@test -n "$$BASECAMP_BACKEND" || (echo "BASECAMP_BACKEND is required" >&2; exit 1)
+	cd kotlin && ./gradlew --quiet :conformance:runReplay
+
 # Run TypeScript conformance tests
 conformance-typescript:
 	@echo "==> Running TypeScript conformance tests..."
@@ -408,11 +424,27 @@ conformance-ruby:
 	@echo "==> Running Ruby conformance tests..."
 	cd conformance/runner/ruby && bundle install --quiet && ruby runner.rb
 
+# Run Ruby wire-replay against snapshots written by the TS live runner.
+# Required env: WIRE_REPLAY_DIR, BASECAMP_BACKEND. Opt-in: not in `make check`.
+conformance-ruby-replay:
+	@echo "==> Running Ruby wire-replay runner..."
+	@test -n "$$WIRE_REPLAY_DIR" || (echo "WIRE_REPLAY_DIR is required" >&2; exit 1)
+	@test -n "$$BASECAMP_BACKEND" || (echo "BASECAMP_BACKEND is required" >&2; exit 1)
+	cd conformance/runner/ruby && bundle install --quiet && ruby replay-runner.rb
+
 # Run Python conformance tests
 conformance-python:
 	@echo "==> Running Python conformance tests..."
 	cd conformance/runner/python && uv sync && uv run python runner.py
 
+# Run Python wire-replay against snapshots written by the TS live runner.
+# Required env: WIRE_REPLAY_DIR, BASECAMP_BACKEND. Opt-in: not in `make check`.
+conformance-python-replay:
+	@echo "==> Running Python wire-replay runner..."
+	@test -n "$$WIRE_REPLAY_DIR" || (echo "WIRE_REPLAY_DIR is required" >&2; exit 1)
+	@test -n "$$BASECAMP_BACKEND" || (echo "BASECAMP_BACKEND is required" >&2; exit 1)
+	cd conformance/runner/python && uv sync && uv run python replay_runner.py
+
 # Run all conformance tests
 conformance: conformance-go conformance-kotlin conformance-typescript conformance-ruby conformance-python
 	@echo "==> Conformance tests passed"
@@ -678,13 +710,18 @@ help:
 	@echo "  swift-clean      Remove Swift build artifacts"
 	@echo ""
 	@echo "Conformance:"
-	@echo "  conformance            Run all conformance tests"
-	@echo "  conformance-go         Run Go conformance tests"
-	@echo "  conformance-kotlin     Run Kotlin conformance tests"
-	@echo "  conformance-typescript Run TypeScript conformance tests"
-	@echo "  conformance-ruby       Run Ruby conformance tests"
-	@echo "  conformance-python     Run Python conformance tests"
-	@echo "  conformance-build      Build Go conformance test runner"
+	@echo "  conformance                Run all conformance tests"
+	@echo "  conformance-go             Run Go conformance tests"
+	@echo "  conformance-go-replay      Decode TS-captured wire snapshots through Go SDK"
+	@echo "  conformance-kotlin         Run Kotlin conformance tests"
+	@echo "  conformance-kotlin-replay  Decode TS-captured wire snapshots through Kotlin SDK"
+	@echo "  conformance-typescript     Run TypeScript conformance tests"
+	@echo "  conformance-typescript-live Run TypeScript live canary against a real backend"
+	@echo "  conformance-ruby           Run Ruby conformance tests"
+	@echo "  conformance-ruby-replay    Decode TS-captured wire snapshots through Ruby SDK"
+	@echo "  conformance-python         Run Python conformance tests"
+	@echo "  conformance-python-replay  Decode TS-captured wire snapshots through Python SDK"
+	@echo "  conformance-build          Build Go conformance test runner"
 	@echo ""
 	@echo "Ruby SDK:"
 	@echo "  rb-generate          Generate types and metadata from OpenAPI"

conformance/runner/go/main.go

@@ -107,6 +107,29 @@ type TestResult struct {
 }
 
 func main() {
+	// Wire-replay mode gate: when WIRE_REPLAY_DIR is set, dispatch to
+	// the replay runner (replay_runner.go) and exit. The replay runner
+	// consumes wire snapshots written by the canonical TS live runner;
+	// see conformance/runner/typescript/live-runner.test.ts. Mock mode
+	// (the rest of this function) runs only when the gate is unset.
+	if dir := os.Getenv("WIRE_REPLAY_DIR"); dir != "" {
+		backend := os.Getenv("BASECAMP_BACKEND")
+		if backend == "" {
+			fmt.Fprintln(os.Stderr, "BASECAMP_BACKEND is required when WIRE_REPLAY_DIR is set")
+			os.Exit(1)
+		}
+		// Match the existing relative-path convention in this file: the
+		// runner is invoked with cwd = conformance/runner/go.
+		fixturePath := filepath.Join("..", "..", "tests", "live-my-surface.json")
+		openapiPath := filepath.Join("..", "..", "..", "openapi.json")
+		runner, err := NewReplayRunner(dir, backend, fixturePath, openapiPath)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
+		os.Exit(runner.Run())
+	}
+
 	testsDir := filepath.Join("..", "..", "tests")
 
 	files, err := filepath.Glob(filepath.Join(testsDir, "*.json"))