Docs/migration 1x to 2x

[ayushiahjolia]

Issue #, if available: N/A

Description of changes:
Migration guide for python v2

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[github-actions]

Claude AI review

Documentation-only PR: a new docs/migration-1.x-to-2.x.md migration guide and an expanded WaitForConditionConfig docstring in packages/aws-durable-execution-sdk-python/src/aws_durable_execution_sdk_python/waits.py.

I verified the guide's technical claims against the source rather than reviewing runtime behavior, since inaccurate migration docs would misdirect users:

• Error hierarchy / exports — DurableOperationError base, StepError/InvokeError/ChildContextError/WaitForConditionError, graded CallbackError subtypes, SerDesError (child of DurableExecutionsError), RetryableSerDesError (retryable InvocationError); all root exports match __init__.py __all__.
• __cause__ — raise_as_operation_error reconstructs a DurableOperationError stand-in (registry fallback to base for non-SDK types) on both first run and replay; the guide's claim is accurate.
• First-run round trip — confirmed in step.py, child.py, wait_for_condition.py; invoke.py does not round-trip, matching "invoke unaffected."
• wait_for_condition — initial_state round-tripped before first check; empty-string payload treated as no stored state, restarting from initial_state.
• wait_for_callback serdes — enclosing child context uses default extended-type serdes, distinct from WaitForCallbackConfig.serdes.
• Completion predicate / BatchResult — should_complete, complete_batch/continue_batch, BatchCompletionError (only CUSTOM_COMPLETION_FAILED), throw_if_error typed raises, and fail-fast map/parallel defaults all match.
• attempt field — required no-default field on StepContext and WaitForConditionCheckContext.
• Removed names — CallableRuntimeError, WaitDecision, ItemBatcher, WaitStrategyConfig.timeout*, etc. confirmed absent.

No inaccurate statements or broken examples found. No actionable findings.

Residual test risk: the guide's code snippets and rg helpers are not covered by doctests/CI, so future API drift wouldn't be caught automatically — acceptable for a docs-only change. Separately (out of scope, not in this diff): the pre-existing DurableOperationError docstring at packages/aws-durable-execution-sdk-python/src/aws_durable_execution_sdk_python/exceptions.py:268-269 states the escaping error "is preserved as __cause__ on the first run," which contradicts the actual reconstruction behavior the new guide correctly documents.

Reviewed commit 6c1c23fe6206a4982795f437c0e251941292116b. Workflow run

[github-actions]

Codex AI review · Finding arf_v1_5ulbaadkrlrjgwsvr6bgmz2tja

P1 — Clarify that fail-fast does not cancel in-flight branches. The executor stops scheduling pending branches after observing a failure, but already-started branches continue; with the default unlimited concurrency, every branch may be submitted before that failure is observed. The current wording can lead users to assume side-effecting branches will not run. Document the in-flight behavior and recommend max_concurrency when users need to bound it.

Suggested change

	**default `map` / `parallel` completion** (which stops after the first failed
	item unless you opt back into process-all).
	**default `map` / `parallel` completion** (which completes after the first
	observed failure and stops scheduling pending items; already-started items are
	not cancelled, so with unlimited concurrency all items may already be running).

[github-actions]

Codex AI review

Found one high-impact documentation issue in the map/parallel migration guidance. No additional defects were confirmed.

Reviewed commit 0edb4a66576ce163f99abf202035da6a37c1cec3. Workflow run