ADR 0003 D2: First-class conflict terms #40

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1. drakestapleton commented on Oct 18, 2026

   

   drakestapleton

   on Oct 18, 2026

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   This was generated by AI.

   claimed by synapse-adr0003 session (Claude Opus 5.5, Synapse vertical). Plan:

   • ConflictTerm in synapse-core: typed entry states (absent, file with mode, directory), sorted add/remove multisets, reduced form, canonical binary encoding.
   • A tree-level sum (adds minus removes, recursive over the Merkle tree, with equal terms cancelling), defined once in core.
   • The B5 rebase rule records conflict terms instead of refusing.
   • A revert derivation rule.
   • Conflict entries in tree nodes, with a per-node conflict count, so materialization (whole-tree file listings) and promotion moves refuse a conflicted tree.

   Tests: rebase twice cancels to a plain three-way conflict, revert returns a clean tree, modify/delete, file/directory and mode conflicts round-trip typed, and conflicted trees are refused for materialization and promotion. Branch synapse/40-conflict-terms.
2. drakestapleton commented on Oct 18, 2026

   

   drakestapleton

   on Oct 18, 2026

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   This was generated by AI.

   D2 is ready on branch synapse/40-conflict-terms (head 0799527), for the orchestrator to open as a PR.

   Stacked on D1: the branch is based on D1's head 18b221e (PR #115), because D2 changes the same derivation code. After #115 merges, rebase with git rebase --onto origin/main 18b221e.

   What it does:

   • A rebase whose paths collide now records typed conflict terms (modify/delete, file/directory, mode, content) instead of being refused.
   • Rebasing twice cancels to a plain three-way conflict.
   • New Revert rule (tag 4) returns a clean tree.
   • Conflicted trees refuse materialization, Git-shaped diffs, Verified and check_promotion.
   • Only derivation rules can record a term.

   It also fixes a C1 bug: the tree store's hash tables were accounted by capacity(), which drops with tombstones, so the high water passed the bound under heavy eviction.

   Tests: workspace 423 passed, 0 failed; clippy -D warnings and fmt are clean. The red script covers 21 mutations, one per behaviour, and all 21 go red. Evidence is in evidence/d2-conflict-terms/; see docs/D2_CONFLICT_TERMS.md section 8 for limits.