[flip-engineer]

Terminal observer retirement records confirmed process absence and successful retirement in call-local state. A repeated retirement request returns without acquiring a new pidfd or signaling the numeric PID again. The live path retains the pidfd bound to the validated attempt and observer custody.

Validation uses PR head 6f1131f39155ea77af34b6612b8dc0a6a2da1d56. The updated process-spawn.c SHA256 is fdbcc59721bb550fe2d0fa898cec5183a94cb64a4639dd4426a495cd4d891a4f.

• The exact-source Linux retirement harness SHA256 is 1f1fb539976a88866043836d3f7315a58b9d95dd831dcc3fe2fcce78615d62e8. It passes known-absence and successful-retirement cases; repeated calls perform zero additional pidfd acquisitions, and unrelated live processes remain alive.
• The composed C source SHA256 is 627a62fb821213bcbfbb54149f0f7823e62f00494fcb67d6b49760c812bbfa6c. It contains the updated source block exactly once; the refresh receipt records unchanged prefix and suffix bytes.
• The four-shard Clang 19 build completed in 131.56 seconds with aggregate peak RSS 5,928,208 KiB. Symbol identity passed, with no duplicate, missing, or type-mismatch symbols. --help output matched the baseline. Binary SHA256: d9dfd8cde346160000663e6b6c32bd8e0654d2a14e0b4e71a2ff0a0bb2749d5e. Build receipt SHA256: 4f96885fc6bb960253e57f6e2485eda5ec40ea75e98c8227423fd5ed417ffce2.
• The live handover fixture passed against that binary. It refused an unrelated PID, completed two consecutive observer handovers, kept the same native process and raw-spool inode, advanced the checkpoint cursor from 175 to 260 to 346, and recorded the task receipt native-reviewed. Root qualification receipt: /var/tmp/root-pr801-final-qualification-20261017/receipt.json, SHA256 df8ff31c658f5080881656728eaecad1712f1b17d53a49be87dedbd6a50560da (live handover passed in 2.344 seconds).
• Independent cgen-clang-review guidance was read by receive attempt 1438 and returned a report with no merge blocker on the tested paths.

The focused harness does not exercise pidfd signal or poll failures. The current recovery path propagates retirement errors; retry behavior after such a failure remains untested.

Compact custody receipt: /var/tmp/root-pr801-final-custody-20261017.json, SHA256 d12a5d14ad06e2e611fc29957b4464e1c1cb7e58b6ca64a91444d0e2729e24cc. It lists exact source, test, refreshed C, refresh/build receipts, binary, fixture, and original harness/live-fixture stdout paths and hashes.