Implement shared-root takeover policy

docs/operations.md

@@ -68,13 +68,13 @@ Published destination bundle paths contain `.distributor.json`. See [Destination
 - Matching destination state: skip as already published.
 - Older destination state for the same source id: replace if transfer policy allows it.
 - Newer destination state for the same source id: skip by default.
-- Valid single-owner state with an identity or source mismatch: replace only when destination `takeover.mode` allows it.
-- Invalid destination state, identity or source mismatches not allowed by `takeover.mode`, or same-created digest mismatch: fail by default.
+- Valid managed state with an identity, source, or shared-root output-owner mismatch: replace only when destination `takeover.mode` allows it.
+- Invalid destination state, identity, source, or shared-root output-owner mismatches not allowed by `takeover.mode`, or same-created digest mismatch: fail by default.
 - Content without `.distributor.json`: fail as unmanaged content by default.
 
 When destination state is older than the source, `transfer.on_destination_older` controls whether publication may proceed and `reconciliation.mode` controls how managed outputs are updated.
 
-For single-owner takeover replacement, `reconciliation.mode: merge` does not retain omitted outputs from the previous source identity. The destination is rewritten as a managed replacement for the current source.
+For takeover replacement, `reconciliation.mode: merge` does not retain omitted outputs from the previous source identity. The destination is rewritten as a managed replacement for the current source or shared-root owner.
 
 `reconciliation.mode: replace` is the default. It deletes only managed output paths recorded in `.distributor.json` plus the state file, verifies the destination bundle path is empty, then writes the newly planned outputs and state. The new state `outputs` array is exactly the newly planned output set.
 
@@ -82,11 +82,11 @@ For single-owner takeover replacement, `reconciliation.mode: merge` does not ret
 
 For both modes, retained or overwritten paths are identified only from `.distributor.json`; unmanaged files are not adopted.
 
-For `state.mode: shared_root`, one destination root may contain outputs from multiple pipeline/destination owners. Comparisons, replacement, and merge retention are scoped to the current owner. Outputs owned by other owners are preserved. A planned output path owned by another owner fails as a conflict, and a planned path that exists in storage but is not recorded in state fails as unmanaged content by default.
+For `state.mode: shared_root`, one destination root may contain outputs from multiple pipeline/destination owners. Comparisons, replacement, and merge retention are scoped to the current owner. Outputs owned by other owners are preserved unless a planned output path is owned by another valid owner and `takeover.mode` allows moving that path to the current owner. A planned path that exists in storage but is not recorded in state fails as unmanaged content by default.
 
 If `state.mode: shared_root` is configured on a destination whose existing single-owner state belongs to the same pipeline and destination, the next successful publish converts that state file to shared-root schema. Existing single-owner state for a different pipeline or destination remains a conflict.
 
-If a write fails after some outputs were written, `distributor` attempts cleanup before returning the error. In `replace` mode, cleanup removes outputs written during that failed attempt. In `merge` mode, cleanup removes only newly created outputs from that failed attempt; overwritten managed outputs are left in place because they previously belonged to the managed set. Operators should still inspect the destination after a failed write before retrying.
+If a write fails after some outputs were written, `distributor` attempts cleanup before returning the error. In `replace` mode and takeover replacement, cleanup removes outputs written during that failed attempt. In same-source `merge` mode, cleanup removes only newly created outputs from that failed attempt; overwritten managed outputs are left in place because they previously belonged to the managed set. Operators should still inspect the destination after a failed write before retrying.
 
 Fan-out destinations are independent. If one destination fails after planning or execution begins, later destinations are still attempted. The command exits non-zero if any destination failed.
 
@@ -153,13 +153,13 @@ For single-owner state, the state owner must match the selected pipeline and des
 
 `run --dry-run` loads config, resolves credentials, discovers source bundles, opens destinations, inspects destination state, builds publish plans, and prints actions. It does not write outputs, `.distributor.json`, or SSH `known_hosts` entries. For reconciliation, dry runs report the same high-level action labels as execution; inspect the configured destination's `reconciliation.mode` to determine whether `replace_older` will replace the managed set or merge into it.
 
-For shared-root destinations, dry runs are owner-scoped. A `replace_older` action replaces or merges only the current owner according to `reconciliation.mode`; unrelated owners remain managed by the shared-root state. Paths owned by another owner still fail as conflicts.
+For shared-root destinations, dry runs are owner-scoped. A `replace_older` action replaces or merges only the current owner according to `reconciliation.mode`; unrelated owners remain managed by the shared-root state. Paths owned by another owner fail as conflicts unless `takeover.mode` allows ownership transfer.
 
 Review these action labels before publishing:
 
 - `publish_new`: destination state is absent, or a shared-root owner is absent and planned paths are publishable.
 - `replace_older`: destination state is older than the source.
-- `replace_takeover`: single-owner destination state is valid managed state and `takeover.mode` allows replacement across an identity or source mismatch.
+- `replace_takeover`: destination state is valid managed state and `takeover.mode` allows replacement across an identity, source, or shared-root output-owner mismatch.
 - `skip_same`: destination state already matches the source.
 - `skip_destination_newer`: destination state is newer than the source and is skipped.
 - `force_replace`: destructive replacement selected because `--force` is present and policy permits it.
@@ -286,7 +286,7 @@ Use these recovery boundaries:
 - For source validation failures, regenerate the source bundle and manifest together.
 - For an empty or missing destination, rerun after fixing config or storage access.
 - For unmanaged destination content, move unrelated files aside or use a different destination path before publishing.
-- For shared-root ownership conflicts, change one owner so it writes a different destination path, or use a separate destination root.
+- For shared-root ownership conflicts, change one owner so it writes a different destination path, use a separate destination root, or configure `takeover.mode` when the current owner should take over valid managed output paths.
 - For missing managed output files recorded in state, run `reconcile-state --dry-run`, then apply `reconcile-state` if the missing files should no longer be considered managed.
 - For configured retention cleanup, run `prune --dry-run`, then apply `prune --apply` after reviewing the managed output list.
 - For failed writes, inspect the destination bundle path, remove only confirmed partial outputs if needed, then rerun `--dry-run`. In merge mode, retained outputs may be intentional managed outputs from the prior state.