A1 — AI-fallback comment_id nondeterminism: parsed comment_time is model
output and not stable across Lambda async retries, so on the ai_fallback
path the comment_id range-key time segment now derives from the email Date
header (deterministic per S3 object) instead of the model's comment_time.
The template path is unchanged (its comment_time is a pure function of the
raw email). Bedrock invoke pins temperature 0 so retries reproduce the same
extraction. Closes the #23 reopening on the AI path.
A2 — EMF record now carries the spec-required _aws.Timestamp (epoch ms) so
CloudWatch reliably extracts the ParseOutcome datapoint that the
fallback-rate alarm depends on.
A3 — T1 New Comment capture no longer truncates at the first blank line;
multi-paragraph comments are captured through internal blanks and terminate
at the next label/separator. 17 golden files regenerated from the real
fixtures accordingly.
Hardening from the sh-security-review pass on this diff:
- _header_date_iso is total: OverflowError/OSError from an extreme Date
header fall back to 'nocomment' instead of failing the invocation.
- _capture_block trims blanks in O(n) (no pop(0)) — removes a quadratic
path on a crafted large blank run.
- work_order_id is enforced digits-only on BOTH parse paths before it is
used as a DynamoDB key, so prompt-injected AI output cannot forge '#'
range-key segments or land on an arbitrary WO.
The workorder-email-processor sends every one of ~22.9k emails/month to
an LLM, but ~93.6% are the plain-text "AMAZON UPDATE WO DETAILS" comment
template and ~6.4% the HTML "AMAZON assign Work Order" template. Parse
those two shapes deterministically, offline, so the AI call is reserved
for the long tail.
The module is pure (no boto3, no network). try_deterministic_parse
classifies by subject, extracts the shared contract fields, and returns
a result ONLY when it passes a strict fail-closed validation gate: exact
contract-key set, subject/id agreement, the literal "Work Order: <id>"
double space, per-type required fields, site-code shape, and a
label-bleed guard so a value that over-ran into the next field fails.
Any miss, drift, or extractor exception yields None so the caller falls
back to the AI extractor -- data is never corrupted, only the fallback
rate rises.
Refs: #23
