diff --git a/exemplars/journal_preposition_huttunen.toml b/exemplars/journal_preposition_huttunen.toml
new file mode 100644
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+++ b/exemplars/journal_preposition_huttunen.toml
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+# Source: derived from a real-world entry in the user's HML draft (Huttunen
+# and Kortelainen, JASIST 72, no. 7, 2021). Promoted to exemplar during
+# real-draft testing on 2026-04-11 after the formatter was observed
+# capitalizing "Among" mid-title, violating CMOS 8.159 ("lowercase
+# prepositions regardless of length in headline-style capitalization").
+#
+# The article title contains four words that CMOS 8.159 requires lowercase
+# in headline-style caps: "on" (prep), "in" (prep), "a" (article), and
+# "among" (prep). The formatter was observed inconsistently capitalizing
+# "among" specifically — some HML entries correct, some not — which is
+# the smoking-gun evidence of nondeterministic judgment drift the runtime
+# validator cannot catch (it checks structural properties, not CMOS
+# capitalization rules).
+#
+# Also exercises:
+# - Curly quote → straight quote normalization
+# - ASCII hyphen in page range → en-dash, no elision (crosses 800 boundary)
+# - Two-author form: first inverted, second in First-Last order (rule 1)
+#
+# Note on simplification: the HML source entry contained U+2010 (non-
+# breaking hyphen) in "Meaning‐Making", a docx→txt conversion artifact.
+# This exemplar uses ASCII hyphen (U+002D) to avoid conflating two
+# independent failure modes (preposition capitalization vs. Unicode
+# hyphen normalization). The U+2010 issue is a separate finding and
+# should be addressed in its own iteration if pursued.
+source = "user draft (HML Submission); article: Huttunen and Kortelainen, JASIST 72, no. 7 (2021), https://doi.org/10.1002/asi.24447"
+type = "journal"
+tags = ["journal", "two-author", "cmos-8.159", "headline-case", "preposition"]
+canary = true
+messy_input = "Huttunen, Aira, and Terttu Kortelainen. “Meaning-Making on Gender: Deeply Meaningful Information in a Significant Life Change among Transgender People.” Journal of the Association for Information Science and Technology 72, no. 7 (2021): 799-810. https://doi.org/10.1002/asi.24447."
+expected_bibliography = "Huttunen, Aira, and Terttu Kortelainen. \"Meaning-Making on Gender: Deeply Meaningful Information in a Significant Life Change among Transgender People.\" *Journal of the Association for Information Science and Technology* 72, no. 7 (2021): 799–810. https://doi.org/10.1002/asi.24447."
+
+[canonical]
+authors = "Huttunen, Aira, and Terttu Kortelainen"
+article_title = "Meaning-Making on Gender: Deeply Meaningful Information in a Significant Life Change among Transgender People"
+journal = "Journal of the Association for Information Science and Technology"
+volume = 72
+issue = 7
+year = 2021
+pages = "799–810"
+doi = "https://doi.org/10.1002/asi.24447"
diff --git a/exemplars/journal_preposition_mehra.toml b/exemplars/journal_preposition_mehra.toml
new file mode 100644
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+++ b/exemplars/journal_preposition_mehra.toml
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+# Source: derived from a real-world entry in the user's HML draft (Mehra,
+# Library Quarterly 91, no. 2, 2021). Promoted to exemplar during real-draft
+# testing on 2026-04-11 after the formatter was observed capitalizing
+# "Beyond" mid-title, violating CMOS 8.159 ("lowercase prepositions
+# regardless of length in headline-style capitalization").
+#
+# This exemplar complements journal_preposition_huttunen.toml with a
+# different preposition ("beyond" instead of "among"), which verifies that
+# new prompt rule 29 generalizes across the preposition list rather than
+# getting memorized for a single word.
+#
+# Also exercises:
+# - Mid-title exclamation point in the article title ("Enough Crocodile
+#   Tears!") must be preserved verbatim, not replaced with a period
+#   (rule 25)
+# - Leading "The" dropped from the periodical name: "The Library Quarterly"
+#   → "Library Quarterly" (rule 17)
+# - Inclusive-number elision within the 110–199 band: 137-149 → 137–49
+#   (rule 24)
+# - Curly quote → straight quote normalization
+source = "user draft (HML Submission); article: Mehra, Library Quarterly 91, no. 2 (2021), https://doi.org/10.1086/713046"
+type = "journal"
+tags = ["journal", "single-author", "cmos-8.159", "headline-case", "preposition", "leading-the-drop", "terminal-punctuation"]
+canary = true
+messy_input = "Mehra, Bharat. “Enough Crocodile Tears! Libraries Moving beyond Performative Antiracist Politics.” The Library Quarterly 91, no. 2 (2021): 137-149. https://doi.org/10.1086/713046."
+expected_bibliography = "Mehra, Bharat. \"Enough Crocodile Tears! Libraries Moving beyond Performative Antiracist Politics.\" *Library Quarterly* 91, no. 2 (2021): 137–49. https://doi.org/10.1086/713046."
+
+[canonical]
+author = "Mehra, Bharat"
+article_title = "Enough Crocodile Tears! Libraries Moving beyond Performative Antiracist Politics"
+journal = "Library Quarterly"
+volume = 91
+issue = 2
+year = 2021
+pages = "137–49"
+doi = "https://doi.org/10.1086/713046"