Measure delivery output and version costs

docs/roadmap/implementation.md

@@ -1,6 +1,6 @@
 # Computational Efficiency Implementation Plan
 
-**Status:** Stage 1 complete; Stages 2–11 pending.
+**Status:** Stages 1–2 complete; Stages 3–11 pending.
 
 ## Purpose And Baseline
 
@@ -126,6 +126,53 @@ measurement support only.
 **Owners:** Benchmark files in `internal/delivery`, `internal/gotool`,
 `internal/runtimeinfo`, and root delivery fixtures.
 
+**Completion:** Complete. Measurements cover declarations and local
+verification of two deterministic 16 MiB files, prebuilt facade delivery for
+fresh uploads and matching retries, combined output capture and forwarding at
+4 KiB and 8 MiB, and injected and real metadata version access. The local HTTP
+fixture hashes and counts incoming multipart bytes incrementally and streams
+matching files from immutable fixture data. It verifies uploaded identities and
+that retries match all three declared assets without uploading again.
+
+### Delivery, Output, And Runtime Baseline
+
+The baseline is commit `29e1bab`, before production refactoring, using the same
+Go, Git, operating system, processor, benchmark command, and three repetitions
+recorded above. Artifact declaration and preflight fixtures contain two
+deterministic 16 MiB files (33,554,432 binary bytes per operation); setup and
+initial writes are outside the timers. Declaration currently hashes each file,
+and declaration plus local verification therefore measures both hashing passes.
+The facade benchmark uses a committed tagged source fixture and prebuilt
+artifacts, so its time includes local source checks, hashing, HTTP requests, and
+streamed body comparison or upload, but no Go compilation. Fresh hosted state is
+reset outside the timed region for every operation. Retry state is prepared
+before timing. The fixture server retains only digest and size metadata for
+uploads and streams known matching bytes directly from shared fixture content.
+
+Output measurements call the combined writer directly, with forwarding to
+`io.Discard`, then capture its completed buffer. They include the current
+completed-output copy. Runtime fallback measurements call `Version()` repeatedly
+against real build metadata; injected access measures the selection helper's
+injected-version branch. The benchmark process reports its own allocations,
+including local HTTP fixture work; streamed artifact bodies are not buffered by
+the fixture server.
+
+| Measurement | Baseline observations | Final comparison |
+| --- | --- | --- |
+| Artifact declarations, two 16 MiB files | 94.3–95.4 ms; 33,554,432 bytes processed; about 68.9 KB allocated. | Pending Stage 11. |
+| Declarations plus local verification | 186.7–188.4 ms; 33,554,432 binary bytes per each of two passes; about 136.2 KB allocated. | Pending Stage 11. |
+| Facade delivery, fresh uploads | 429–447 ms; 32 MiB binary payload, two files plus manifest; 1.43–1.46 MB allocated. | Pending Stage 11. |
+| Facade delivery, matching retry | 309.1–310.0 ms; 32 MiB of local verification plus streamed remote comparisons; 1.21–1.22 MB allocated. | Pending Stage 11. |
+| Combined output, 4 KiB and `io.Discard` | 1.82–1.87 μs; 8,256 B and 3 allocations per operation. | Pending Stage 11. |
+| Combined output, 8 MiB and `io.Discard` | 2.02–2.36 ms; 16.78 MB and 3 allocations per operation, including the completed capture copy. | Pending Stage 11. |
+| Injected version selection | 0.745–0.754 ns; 0 B and 0 allocations. | Pending Stage 11. |
+| Repeated real metadata fallback | 1.438–1.474 μs; 1,184 B and 7 allocations per operation. | Pending Stage 11. |
+
+The delivery observations include local HTTP and filesystem costs specific to
+these fixtures. The output component benchmark does not include child startup;
+the real delivery benchmark does include HTTP request handling. These results
+describe measured workloads and do not establish runtime guarantees.
+
 1. Extend the same benchmark prefix to declaration/preflight processing of two
    deterministic 16 MiB artifact files. Measure prebuilt facade `Deliver`
    against a local HTTP fixture for fresh uploads and matching retries.