edithatogo · Aug 10, 2026 · Aug 10, 2026 · Aug 10, 2026
diff --git a/README.md b/README.md
@@ -246,6 +246,11 @@ audience: everyone
 section: original-essays
 comments: enabled
 ---
+
+Start the article body here. Do not repeat the front-matter title or subtitle as
+the first heading or paragraph; those values are written to Substack's dedicated
+header fields. The CLI defensively removes exact leading repetitions, but users
+and authoring agents should emit each title and subtitle only once.
 ```
 
 Media examples:

diff --git a/biome.json b/biome.json
@@ -1,5 +1,5 @@
 {
-  "$schema": "https://biomejs.dev/schemas/2.5.3/schema.json",
+  "$schema": "https://biomejs.dev/schemas/2.5.7/schema.json",
   "assist": { "actions": { "source": { "organizeImports": "off" } } },
   "linter": {
     "enabled": true,

diff --git a/conductor/archive/T18-01/contracts.json b/conductor/archive/T18-01/contracts.json
@@ -0,0 +1,7 @@
+{
+  "schemaVersion": 1,
+  "trackId": "T18-01",
+  "contractIds": ["PARSER-AST-006", "FEATURE-FIDELITY-008", "UX-CLI-CONTRACT-005"],
+  "programmeIssue": 184,
+  "project": 38
+}
diff --git a/conductor/archive/T18-01/design.md b/conductor/archive/T18-01/design.md
@@ -0,0 +1,18 @@
+# Design T18-01
+
+```mermaid
+flowchart LR
+  A["Markdown source"] --> B["Parse front matter and body"]
+  B --> C["Resolve title"]
+  C --> D{"Leading block exactly matches title?"}
+  D -->|Yes| E["Remove title block"]
+  D -->|No| F["Preserve block"]
+  E --> G{"Next block exactly matches subtitle?"}
+  F --> G
+  G -->|Yes| H["Remove subtitle block"]
+  G -->|No| I["Preserve body"]
+  H --> J["Synchronized prepared post"]
+  I --> J
+```
+
+Matching uses rendered block text with surrounding whitespace trimmed. Removal is limited to the first eligible title block and immediately leading subtitle block.
diff --git a/conductor/archive/T18-01/implementation.md b/conductor/archive/T18-01/implementation.md
@@ -0,0 +1,7 @@
+# Implementation T18-01
+
+- Exact leading explicit title headings or paragraphs are removed.
+- Heading-derived title fallback remains supported when front matter has no title.
+- Exact leading subtitle headings or paragraphs are removed after title normalization.
+- Markdown, HTML, and ProseMirror representations remain synchronized.
+- Canonical examples and agent/user guidance no longer repeat header metadata.
diff --git a/conductor/archive/T18-01/index.md b/conductor/archive/T18-01/index.md
@@ -0,0 +1,9 @@
+# T18-01 Metadata/body de-duplication correctness
+
+- [Specification](./spec.md)
+- [Requirements](./requirements.md)
+- [Design](./design.md)
+- [Plan](./plan.md)
+- [Verification](./verification.md)
+- [Metadata](./metadata.json)
+- [GitHub issue #537](https://github.com/edithatogo/substack-cli-ts/issues/537)
diff --git a/conductor/archive/T18-01/metadata.json b/conductor/archive/T18-01/metadata.json
@@ -0,0 +1,12 @@
+{
+  "trackId": "T18-01",
+  "title": "Metadata/body de-duplication correctness",
+  "type": "bug",
+  "status": "archived",
+  "parentIssue": 538,
+  "issue": 537,
+  "project": 38,
+  "createdAt": "2026-08-10T23:30:00+10:00",
+  "updatedAt": "2026-08-10T23:55:00+10:00",
+  "archivedAt": "2026-08-10T23:55:00+10:00"
+}
diff --git a/conductor/archive/T18-01/plan.md b/conductor/archive/T18-01/plan.md
@@ -0,0 +1,23 @@
+# Plan T18-01
+
+## Phase 1: Reproduction and contract
+
+- [x] Task: Reproduce title/subtitle metadata duplication and identify all shared preparation paths.
+- [x] Task: Define MoSCoW requirements, risks, and Mermaid design.
+- [x] Task: Register P18/T18-01 and nested task issues.
+- [x] Task: Phase verification and checkpoint per `conductor/workflow.md`.
+
+## Phase 2: Test-driven correction
+
+- [x] Task: Add exact title/subtitle and formatting regression tests.
+- [x] Task: Add mismatch, later-match, and fallback preservation tests.
+- [x] Task: Normalize leading metadata blocks at `preparePost()`.
+- [x] Task: Phase verification and checkpoint per `conductor/workflow.md`.
+
+## Phase 3: Guidance and closeout
+
+- [x] Task: Correct checked-in examples and document canonical agent/user input.
+- [x] Task: Apply review finding for explicit paragraph title duplication.
+- [x] Task: Run focused and required hosted verification.
+- [x] Task: Review Actions and comments, merge, archive, and clean up.
+- [x] Task: Phase verification and checkpoint per `conductor/workflow.md`.
diff --git a/conductor/archive/T18-01/requirements.md b/conductor/archive/T18-01/requirements.md
@@ -0,0 +1,21 @@
+# Requirements T18-01
+
+## Must
+
+- Remove exact leading metadata repetitions at the shared preparation boundary.
+- Keep Markdown, HTML, and ProseMirror representations synchronized.
+- Add deterministic regression and preservation tests.
+- Correct examples and document the agent authoring contract.
+
+## Should
+
+- Treat inline formatting as presentation rather than a text mismatch.
+- Preserve title fallback when title front matter is absent.
+
+## Could
+
+- Add future diagnostics for near-matching title/deck content.
+
+## Won't
+
+- Remove content based on fuzzy, semantic, or LLM judgment.
diff --git a/conductor/archive/T18-01/risks.md b/conductor/archive/T18-01/risks.md
@@ -0,0 +1,5 @@
+# Risks T18-01
+
+- Over-broad deletion could remove legitimate editorial content; exact rendered-text equality and leading-position constraints mitigate this.
+- Divergence between Markdown, HTML, and ProseMirror forms could affect validation; all three are normalized together and tested.
+- Agent guidance alone is insufficient; the shared runtime boundary remains defensive.
diff --git a/conductor/archive/T18-01/spec.md b/conductor/archive/T18-01/spec.md
@@ -0,0 +1,19 @@
+# Track T18-01: Metadata/body de-duplication correctness
+
+## Overview
+
+Prevent front-matter title and subtitle values from appearing again at the start of the article body while preserving legitimate editorial content and heading-derived title fallback.
+
+## Acceptance criteria
+
+- Exact leading title headings and subtitle paragraphs/headings are absent from prepared Markdown, HTML, and ProseMirror content.
+- Formatting does not prevent exact rendered subtitle matching.
+- Non-matching headings, standfirsts, and later matching text remain untouched.
+- Title fallback from a leading heading without front matter remains supported.
+- Examples and agent-facing guidance use one canonical metadata/body shape.
+
+## Out of scope
+
+- Fuzzy or semantic deletion of similar content.
+- Editing already-created Substack drafts.
+- Changing Substack title or subtitle field selectors.
diff --git a/conductor/archive/T18-01/verification.md b/conductor/archive/T18-01/verification.md
@@ -0,0 +1,11 @@
+# Verification T18-01
+
+- Issue reproduction: confirmed.
+- Focused regression tests: 14 passed.
+- Full test suite: 117 files and 933 tests passed.
+- TypeScript typecheck: passed.
+- Contract generation check: passed.
+- Programme drift check before closeout: passed.
+- Conductor review: one paragraph-title gap found, fixed, and reverified.
+- Required hosted checks: pending PR.
+- Review comments: pending PR.
diff --git a/conductor/contracts/substack-cli-maturity.contract.json b/conductor/contracts/substack-cli-maturity.contract.json
@@ -1701,6 +1701,15 @@
         "T11-03"
       ],
       "status": "planned"
+    },
+    {
+      "phaseId": "P18",
+      "title": "Metadata/body de-duplication correctness",
+      "releaseTarget": "next patch",
+      "tracks": [
+        "T18-01"
+      ],
+      "status": "contract_verified"
     }
   ],
   "tracks": [
@@ -2571,6 +2580,26 @@
         "url": "https://github.com/edithatogo/substack-cli-ts/issues/457",
         "title": "T11-03 Prompt retirement and canonical-system handover"
       }
+    },
+    {
+      "id": "T18-01",
+      "phaseId": "P18",
+      "title": "Metadata/body de-duplication correctness",
+      "status": "contract_verified",
+      "contractIds": [
+        "PARSER-AST-006",
+        "FEATURE-FIDELITY-008",
+        "UX-CLI-CONTRACT-005"
+      ],
+      "requiredTaskCount": 3,
+      "existingIssues": [
+        537
+      ],
+      "issue": {
+        "number": 537,
+        "url": "https://github.com/edithatogo/substack-cli-ts/issues/537",
+        "title": "Prevent title and subtitle duplication in published post bodies"
+      }
     }
   ],
   "tasks": [
@@ -7095,6 +7124,75 @@
         "GOV-PROMPT-RETIREMENT-006"
       ],
       "release": "1.0 and beyond"
+    },
+    {
+      "id": "T18-01-TASK-01",
+      "title": "Add metadata-prefix regression coverage",
+      "trackId": "T18-01",
+      "phaseId": "P18",
+      "status": "contract_verified",
+      "contractIds": [
+        "PARSER-AST-006",
+        "FEATURE-FIDELITY-008",
+        "UX-CLI-CONTRACT-005"
+      ],
+      "issue": {
+        "number": 539,
+        "url": "https://github.com/edithatogo/substack-cli-ts/issues/539",
+        "title": "Add metadata-prefix regression coverage"
+      },
+      "mustContractIds": [
+        "PARSER-AST-006",
+        "FEATURE-FIDELITY-008",
+        "UX-CLI-CONTRACT-005"
+      ],
+      "release": "next patch"
+    },
+    {
+      "id": "T18-01-TASK-02",
+      "title": "Normalize exact title and subtitle prefixes",
+      "trackId": "T18-01",
+      "phaseId": "P18",
+      "status": "contract_verified",
+      "contractIds": [
+        "PARSER-AST-006",
+        "FEATURE-FIDELITY-008",
+        "UX-CLI-CONTRACT-005"
+      ],
+      "issue": {
+        "number": 540,
+        "url": "https://github.com/edithatogo/substack-cli-ts/issues/540",
+        "title": "Normalize exact title and subtitle prefixes"
+      },
+      "mustContractIds": [
+        "PARSER-AST-006",
+        "FEATURE-FIDELITY-008",
+        "UX-CLI-CONTRACT-005"
+      ],
+      "release": "next patch"
+    },
+    {
+      "id": "T18-01-TASK-03",
+      "title": "Correct examples and agent authoring guidance",
+      "trackId": "T18-01",
+      "phaseId": "P18",
+      "status": "contract_verified",
+      "contractIds": [
+        "PARSER-AST-006",
+        "FEATURE-FIDELITY-008",
+        "UX-CLI-CONTRACT-005"
+      ],
+      "issue": {
+        "number": 541,
+        "url": "https://github.com/edithatogo/substack-cli-ts/issues/541",
+        "title": "Correct examples and agent authoring guidance"
+      },
+      "mustContractIds": [
+        "PARSER-AST-006",
+        "FEATURE-FIDELITY-008",
+        "UX-CLI-CONTRACT-005"
+      ],
+      "release": "next patch"
     }
   ],
   "issueMap": {
@@ -7175,6 +7273,11 @@
         "url": "https://github.com/edithatogo/substack-cli-ts/issues/446",
         "title": "P11 1.0 governance and post-1.0 roadmap",
         "parentPhaseLink": "already"
+      },
+      "P18": {
+        "number": 538,
+        "url": "https://github.com/edithatogo/substack-cli-ts/issues/538",
+        "title": "P18 Metadata/body de-duplication correctness"
       }
     },
     "trackIssues": {
@@ -7453,6 +7556,12 @@
         "url": "https://github.com/edithatogo/substack-cli-ts/issues/457",
         "title": "T11-03 Prompt retirement and canonical-system handover",
         "parentTrackLink": "already"
+      },
+      "T18-01": {
+        "number": 537,
+        "url": "https://github.com/edithatogo/substack-cli-ts/issues/537",
+        "title": "Prevent title and subtitle duplication in published post bodies",
+        "parentTrackLink": "already"
       }
     },
     "taskIssues": {
@@ -8601,6 +8710,24 @@
         "url": "https://github.com/edithatogo/substack-cli-ts/issues/461",
         "title": "T11-03 T11-03-TASK-04",
         "parentTaskLink": "already"
+      },
+      "T18-01-TASK-01": {
+        "number": 539,
+        "url": "https://github.com/edithatogo/substack-cli-ts/issues/539",
+        "title": "Add metadata-prefix regression coverage",
+        "parentTaskLink": "already"
+      },
+      "T18-01-TASK-02": {
+        "number": 540,
+        "url": "https://github.com/edithatogo/substack-cli-ts/issues/540",
+        "title": "Normalize exact title and subtitle prefixes",
+        "parentTaskLink": "already"
+      },
+      "T18-01-TASK-03": {
+        "number": 541,
+        "url": "https://github.com/edithatogo/substack-cli-ts/issues/541",
+        "title": "Correct examples and agent authoring guidance",
+        "parentTaskLink": "already"
       }
     }
   },

diff --git a/conductor/programme-state.json b/conductor/programme-state.json
@@ -84,6 +84,12 @@
       "issue": 446,
       "state": "OPEN",
       "status": "Todo"
+    },
+    {
+      "id": "P18",
+      "issue": 538,
+      "state": "CLOSED",
+      "status": "Done"
     }
   ],
   "tracks": [
@@ -454,6 +460,14 @@
       "state": "OPEN",
       "status": "Todo",
       "evidence": "conductor/tracks/T11-03/verification.md"
+    },
+    {
+      "id": "T18-01",
+      "phase": "P18",
+      "issue": 537,
+      "state": "CLOSED",
+      "status": "Done",
+      "evidence": "conductor/archive/T18-01/verification.md"
     }
   ],
   "tasks": [
@@ -1984,6 +1998,30 @@
       "state": "OPEN",
       "status": "Todo",
       "evidence": "conductor/tracks/T11-03/verification.md"
+    },
+    {
+      "id": "T18-01-TASK-01",
+      "track": "T18-01",
+      "issue": 539,
+      "state": "CLOSED",
+      "status": "Done",
+      "evidence": "conductor/archive/T18-01/verification.md"
+    },
+    {
+      "id": "T18-01-TASK-02",
+      "track": "T18-01",
+      "issue": 540,
+      "state": "CLOSED",
+      "status": "Done",
+      "evidence": "conductor/archive/T18-01/verification.md"
+    },
+    {
+      "id": "T18-01-TASK-03",
+      "track": "T18-01",
+      "issue": 541,
+      "state": "CLOSED",
+      "status": "Done",
+      "evidence": "conductor/archive/T18-01/verification.md"
     }
   ],
   "supplemental": [