narratio/docs/roadmap/implementation.md

Workstream 1 Implementation Plan

Purpose And Status

This document is the executable implementation plan for refactoring.md, Workstream 1: Go baseline, process supervision, and transcription concurrency. The refactoring roadmap owns the approved scope, rationale, and target state; the Audit Decision Register records the controlling audit dispositions. This plan translates that settled direction into six bounded stages suitable for one gpt-5.6-terra coding prompt apiece.

All stages are pending and must be implemented in numeric order. Workstreams 2 and later are out of scope. In particular, this plan routes adapter-owned file replacement through the existing internal/fileops owner but does not perform the broader FileOps simplification reserved for Workstream 2.

Settled Implementation Decisions

The following decisions are final for this implementation:

• The maintained language baseline is Go 1.26. The module directive is go 1.26.0; ordinary verification and scheduled CI use the official golang:1.26 image, while tag CI uses the current explicitly pinned Go 1.26 patch image, golang:1.26.7. The release-workflow documentation check must assert that same pinned tag. Do not retain a Go 1.25 execution path.
• Go 1.26 is adopted before code relies on os.Process.WithHandle. Existing release semantics, supported build targets, and the rule that tag push—not asynchronous CI completion—is the synchronous release boundary do not change.
• golang.org/x/sync/errgroup is the only new dependency. Add golang.org/x/sync v0.22.0 as a direct dependency when transcription starts using it, then run go mod tidy. Do not add an external subprocess, worker-pool, filesystem, or error framework.
• subprocess.Run, subprocess.RunRequest, and subprocess.RunResult remain the adapter-facing contract. Their retained behavior includes environment allowlisting and overrides, sensitive-value redaction, separate or shared bounded diagnostics, timeouts and cancellation, process-tree termination, reaping, exit information, error wrapping, and tool-specific diagnostic hints.
• Split the existing subprocess implementation inside the current internal/adapters/subprocess package. Do not create a public API, a new repository package, or an external module. A private execution mechanism owns process-tree creation, start, wait, interruption, bounded termination, reaping, disposal, timestamps, exit state, and typed termination outcomes. The existing Run boundary remains the Narratio policy wrapper and owns request validation, timeout construction, environment selection, command arguments and working directory, diagnostic paths and modes, bounded and redacted sinks, public result mapping, diagnostic wording, and hints.
• Represent the mechanism result with a private outcome type and private reason enum that distinguish: not started/start failure, natural exit, parent cancellation, deadline expiry, and external abort (currently a diagnostic-size limit). Preserve the underlying start, wait, context, abort, and cleanup errors as separate fields so the policy layer can retain errors.Is/errors.As behavior and join secondary cleanup failures without replacing the primary classification.
• The mechanism accepts an already policy-configured *exec.Cmd and a generic <-chan error abort signal. It must not import internal/fileops, inspect environment variables or secrets, open diagnostic paths, know diagnostic byte limits or owners, marshal configuration, or construct Narratio-facing error text. The policy wrapper must not directly start, wait for, kill, or reap the command.
• On Windows, continue creating the process suspended, configure a kill-on-close Job Object, assign the child before resuming its initial thread, and fail closed on every setup error. Perform assignment inside cmd.Process.WithHandle, converting the callback's uintptr to windows.Handle only for windows.AssignProcessToJobObject. Capture the callback's assignment error separately from the error returned by WithHandle. Remove the PID-based windows.OpenProcess and its associated process-handle close; do not change the thread-discovery/resumption or job disposal behavior.
• Remove WriteYAMLAtomic and WriteFileAtomic from the subprocess package. Each of audita, scriptorium, and seriatim owns a small private writeGeneratedYAML helper that marshals its generated configuration with gopkg.in/yaml.v3 and installs the bytes through fileops.WriteFileAtomic using fileops.WorkspaceFileMode. Fake-adapter byte placeholders call fileops.WriteFileAtomic directly. Do not create a new generic adapter-I/O package merely to preserve the old wrapper.
• Generated configuration must continue to omit API-key values. Preserve the current schemas and semantic content; incidental YAML key order and exact wrapper punctuation are not contracts.
• Replace the transcription channel/worker/first-error implementation with errgroup.WithContext and SetLimit. Submit one closure per prepared audio job, use the errgroup context for every WhisperX call, and return speaker-qualified adapter, authoritative-output, and JSON-validation errors directly from that closure. Errgroup cancellation replaces the manual cancel-on-first-error path.
• The transcription mutex protects successful shared aggregation only. It must not coordinate errors or adapter execution. Canonical materialization still begins only after every job succeeds and still occurs in sorted speaker order. A parent cancellation returns an error wrapping the parent context error and reports completed versus planned work; it does not need to retain the current incidental “dispatched” count.
• Tests protect observable outcomes and cross-platform compilation, not the exact internal helper graph, exact full diagnostic strings, or the literal syscall sequence. Native Windows behavior must not be claimed where only a Windows cross-compile is available.
• The original audits and decision records are historical inputs. Do not rewrite them during implementation. Mark Workstream 1 Complete in refactoring.md only after all six stages and final validation succeed.

Instructions For Every Stage

Before changing files in each stage:

1. Read docs/development.md, every document under docs/policy/, this plan, and Workstream 1 plus the dependency and target-state sections of refactoring.md.
2. Consult the relevant entries H11, H19, H22, H24, H33, and L01 in audit-decisions.md. Use library-audit.md only for its subprocess-incubation rationale; its “extract later” possibility is not current scope.
3. Inspect the current implementation and focused tests named by the stage. Prefer the codebase knowledge graph for Go discovery and use text search for YAML, shell, Markdown, literals, and generated configuration.
4. Confirm the worktree state and preserve unrelated changes. Do not begin a later workstream merely because adjacent code would also benefit from it.

During every stage:

• Keep package ownership and dependency direction consistent with docs/policy/architecture.md. Prefer private types and focused files to a new architectural layer.
• Keep API keys out of arguments where the adapter contract already uses the environment, and out of generated configuration, logs, errors, fixtures, and test output. Ordinary workspace files retain group-owned modes.
• Preserve supported Linux, macOS, and Windows behavior. Use build constraints for platform-specific process code and do not add a permissive unsupported- platform fallback.
• Keep tests deterministic, offline, and behavior-focused. Exercise configured and observed concurrency, retain errors.Is/errors.As assertions where meaningful, and avoid freezing complete error wording or private helper choreography.
• Update canonical current-behavior documentation in the same stage that makes a behavior current. Roadmap documents may describe future work; canonical docs may not.
• Run gofmt on changed Go files, go mod tidy when module state changes, focused tests while iterating, and git diff --check before completing the stage. Mark a stage Completed only after all of its exit criteria pass.

Stage 1 — Establish The Go 1.26 Baseline

Status: Completed

Goal

Move every maintained build and release surface to Go 1.26 before introducing Go 1.26-only process APIs.

Required Work

1. Change the module directive in go.mod from go 1.25.0 to go 1.26.0. Run GOWORK=off go mod tidy with Go 1.26 and commit any resulting go.mod/go.sum changes. Do not add x/sync in this stage; it becomes a used direct dependency in Stage 5.
2. Update every Go step in .woodpecker/verify.yml and .woodpecker/shuffle.yml to golang:1.26. Update both Go steps in .woodpecker/release.yml to golang:1.26.7. Preserve workflow triggers, dependency ordering, commands, release-plugin configuration, and the asynchronous release responsibility boundary.
3. Update internal/doccheck/doccheck_test.go so the release workflow contract expects golang:1.26.7 for validation and asset construction. Keep this check semantic: it should still validate the shared candidate checker, asset-builder delegation, step dependencies, and release-plugin settings.
4. Update Go-module fixture text under internal/releasecheck from 1.25 to 1.26 where it represents an otherwise valid synthetic module. Do not change unrelated decimal values such as model/configuration examples.
5. Add a concise Go 1.26 prerequisite to docs/development.md and docs/release.md. In the release document, distinguish the maintained Go 1.26 baseline from the currently pinned tag-CI patch image without changing the release procedure or promising that automation waits for CI.
6. Search maintained source, workflows, scripts, canonical docs, and semantic test fixtures for stale Go 1.25 baseline claims. Historical audit prose may remain historical; controlling roadmap text already records the approved Go 1.26 decision.

Exit Criteria

• go env GOVERSION reports a Go 1.26 toolchain and GOWORK=off go mod tidy -diff succeeds.
• go test ./..., go test -race ./..., go vet ./..., and go build ./... succeed.
• go test ./internal/doccheck and go test ./internal/config -run '^TestExamplesLoadAndValidate$' succeed.
• The six CGO-disabled release targets build through scripts/build-release-assets.sh into a new temporary directory and the host version smoke check succeeds.
• All maintained Go execution surfaces resolve to Go 1.26, and git diff --check succeeds.

Stage 2 — Separate Subprocess Lifecycle Mechanics From Policy

Status: Completed

Goal

Make the process-tree lifecycle an internally reusable, typed mechanism while keeping Narratio-specific environment, diagnostics, redaction, paths, and error presentation at the existing adapter-facing boundary.

Required Work

1. Add internal/adapters/subprocess/execution.go. Move the complete command lifecycle behind one private function that receives a context, an already configured *exec.Cmd, and a generic <-chan error abort signal. The function must:
   • record UTC start/completion times and initialize an unknown exit code;
   • reject an already-done context without starting a child;
   • create the platform-owned process tree;
   • apply the bounded stream WaitDelay before start;
   • start exactly once through the tree owner;
   • wait once in a buffered result channel;
   • on cancellation, deadline, or abort, perform the existing bounded graceful/forceful termination and reaping sequence;
   • dispose the tree on every path after creation; and
   • return a private typed outcome containing its reason, timing, exit code, and separate start, wait, context, abort, and cleanup errors.
2. Keep platform-specific process ownership in process_tree_*.go. Reduce process_tree.go to the owned-tree interface, shared termination intervals, and narrowly reusable termination/reaping helpers needed by execution.go. The lifecycle mechanism, rather than Run, must be the only caller of Start, cmd.Wait, tree termination, and Dispose.
3. Change the diagnostic-limit notification channel in diagnostics.go to the generic error channel accepted by the mechanism. Continue retaining the first concrete *captureLimitError separately so policy formatting can name the stream, diagnostic owner, and configured limit after the command has been reaped. Preserve the exact byte caps, redaction, tail bounds, shared-log locking, flush, and close behavior.
4. Refactor Run in run.go into the policy/composition layer. It must still:
   • validate the executable and normalize a nil parent context;
   • create the optional timeout context;
   • build the allowlisted, overridden child environment;
   • select sensitive values and open bounded redacting log sinks;
   • construct and configure exec.Cmd arguments, working directory, environment, stdout, and stderr;
   • call the private execution mechanism exactly once;
   • flush diagnostics, map the mechanism outcome to RunResult, and format the existing useful start/exit/timeout/cancellation/capture/cleanup categories; and
   • preserve stderr-tail redaction, log paths, bad-descriptor hints, and error chains.
5. Keep RunRequest and RunResult source-compatible for every adapter. Exact punctuation is not required, but existing callers and behavior tests must continue to receive useful executable/argument/path/exit context and errors.Is/errors.As access to cancellation, deadline, exec.ExitError, capture, and cleanup causes.
6. Reorganize run_test.go and process_tree_supported_test.go only where the new boundary makes ownership clearer. Retain public Run coverage for success, environment filtering/override, secrets, separate/shared logs, size limits, timeouts, cancellation, nonzero exit, hinting, and descendant cleanup. Add focused private-mechanism tests only for a typed distinction not already protected through Run; do not duplicate the whole suite or assert private function names.
7. Update internal/adapters/subprocess/doc.go and docs/internal/adapters.md to describe the implemented internal mechanism/policy split. Keep the package internal and do not describe it as a released reusable library.

Exit Criteria

• The lifecycle mechanism has no dependency on fileops, YAML, environment selection, secret catalogs/redaction policy, diagnostic paths or modes, or Narratio-facing error wording.
• Run does not directly start, wait, terminate, reap, or dispose a process, and its public request/result surface is unchanged.
• go test ./internal/adapters/subprocess and go test -race ./internal/adapters/subprocess pass on the native supported host.
• Existing adapter subprocess tests for Audita, Scriptorium, Seriatim, and Notarius pass without loosening credential or diagnostic assertions.
• go test ./..., go vet ./..., go build ./..., and git diff --check succeed.

Stage 3 — Use The Stable Windows Process Handle

Status: Completed

Goal

Eliminate PID reopening during Windows Job Object assignment while preserving the fail-closed suspended-child lifecycle.

Required Work

1. In process_tree_windows.go, keep Job Object creation and JOB_OBJECT_LIMIT_KILL_ON_JOB_CLOSE configuration before child start. Keep windows.CREATE_SUSPENDED on the command.
2. After cmd.Start, call cmd.Process.WithHandle. Inside its callback, call windows.AssignProcessToJobObject(job, windows.Handle(handle)) and store that assignment error in a callback-local variable visible after WithHandle returns. Treat a WithHandle error and an assignment error as distinct setup failures with accurate context.
3. Delete the windows.OpenProcess call, the requested process access-mask constants, and the matching windows.CloseHandle for the reopened process. Never retain or close the handle supplied to the WithHandle callback.
4. Resume the initial thread only after successful assignment. Preserve resumeInitialThread, the suspended process's PID-based thread enumeration, and the existing thread-handle lifetime.
5. On handle acquisition, assignment, or resume failure, kill and wait for the suspended child, close the not-yet-owned Job Object, and return an error that preserves the primary setup cause plus cleanup causes. On success, retain the Job Object in the tree and preserve its kill-on-close disposal behavior.
6. Do not add a test that scans source text for OpenProcess or mocks the standard library. Rely on Go 1.26 Windows compilation for API/type safety and the existing supported-host process-tree behavior tests for lifecycle semantics. If a native Windows runner is unavailable, state that limitation in the implementation-stage handoff rather than claiming runtime coverage.

Exit Criteria

• process_tree_windows.go uses os.Process.WithHandle for Job Object assignment and no longer reopens the child PID as a process handle.
• CGO-disabled Windows amd64 and arm64 builds succeed.
• A Windows test binary for ./internal/adapters/subprocess cross-compiles with go test -c; it is not executed on a non-Windows host.
• Native-host subprocess tests, race tests, repository tests, vet, build, and git diff --check succeed.
• The stage handoff accurately distinguishes cross-compilation from native Windows runtime evidence.

Stage 4 — Remove File Writing From The Subprocess Package

Status: Completed

Goal

Make internal/adapters/subprocess exclusively about command execution and move generated configuration and fake-output persistence to the adapters that own those files.

Required Work

1. Add one unexported writeGeneratedYAML(path string, payload any) error helper within each of the audita, scriptorium, and seriatim adapter packages. A focused generated_config.go file is preferred in each package so production and fake runners share the same tool-owned serialization.
2. In each helper, marshal with yaml.Marshal, wrap marshal failures with the destination path, and install the bytes through fileops.WriteFileAtomic(path, data, fileops.WorkspaceFileMode). Preserve a path-bearing write error and the existing group-owned mode. Do not put API key values into the payload while moving code.
3. Replace every production and fake use of subprocess.WriteYAMLAtomic with its package-local helper. Replace every fake use of subprocess.WriteFileAtomic with a direct fileops.WriteFileAtomic call, keeping the existing operation-specific caller context for outputs, reports, stdout, and stderr placeholders.
4. Remove WriteYAMLAtomic and WriteFileAtomic from internal/adapters/subprocess/run.go, along with now-unused YAML, filesystem, mode, and fileops imports. Update the package comment so it claims only process execution/supervision and Narratio subprocess policy.
5. Delete the two generic YAML-writer tests from subprocess coverage. Do not recreate tests for a trivial private wrapper in all three packages. Instead, retain the existing Audita, Scriptorium, and Seriatim production/fake adapter tests that read generated configurations, check placeholder files, and assert that credentials are absent. Add a focused adapter test only if one migrated output is not already covered at its stable adapter boundary.
6. Search all Go source to prove no caller or reference to the removed subprocess writers remains. Do not move or simplify fileops itself; that package is the temporary focused replacement owner until Workstream 2.

Exit Criteria

• The subprocess package imports neither gopkg.in/yaml.v3 nor internal/fileops and exports no file-writing helper.
• All generated YAML and fake adapter files retain their schemas/content, workspace mode, overwrite behavior, and contextual failures.
• Audita, Scriptorium, and Seriatim production and fake adapter tests pass, including credential-absence checks.
• Subprocess tests pass after removing only writer-specific coverage.
• go test ./..., go test -race ./internal/adapters/..., go vet ./..., go build ./..., and git diff --check succeed.

Stage 5 — Replace The Transcription Worker Pool With Errgroup

Status: Pending

Goal

Use the maintained bounded-concurrency primitive for per-speaker WhisperX work while preserving cancellation, all-or-nothing canonical materialization, and deterministic results.

Required Work

1. Add golang.org/x/sync v0.22.0 as a direct dependency and run GOWORK=off go mod tidy. Import golang.org/x/sync/errgroup in internal/stage/transcribe.go.
2. Preserve all pre-concurrency behavior: environment validation, session and run-layout resolution, prepared-audio discovery, positive/default concurrency calculation, duplicate speaker rejection, and deterministic job construction.
3. Replace the explicit context.WithCancel, worker count, jobs channel, sync.WaitGroup, dispatch loop, and mutex-protected firstErr with:
   • group, groupCtx := errgroup.WithContext(ctx);
   • group.SetLimit(concurrency); and
   • one group.Go closure per prepared job, capturing a per-iteration job value and checking groupCtx before beginning expensive work.
4. Each closure calls env.WhisperX.Transcribe with groupCtx, validates the authoritative output path, validates the run-local transcript JSON, and returns immediately on failure. Every returned failure must identify the speaker; adapter failures should also retain the audio basename, and output failures should retain the relevant output path. Do not store a shared first error or call a manual cancel function.
5. On success, build that speaker's metadata locally, then lock only long enough to add it to perFile and increment completed. Do not keep a shared map of output refs: each job's planned run-local path is already in the immutable job list and can be used after group.Wait succeeds.
6. After submissions, call group.Wait exactly once. Read completed under the same mutex before constructing any diagnostic. Apply this result order:
   • if the parent ctx.Err() is non-nil, return a transcribe cancellation error that reports completed and total jobs and wraps that parent error;
   • otherwise, if group.Wait returned an error, return its speaker-qualified failure; and
   • otherwise, require completed == len(jobs) as an internal completeness guard. A closure admitted after errgroup cancellation may return the group context error without invoking WhisperX; the first originating errgroup error remains authoritative.
7. Preserve the post-success transaction boundary. Sort speaker IDs, then materialize each planned run-local output to the canonical transcript path serially in that order. Preserve ordered outputs, run/canonical path metadata, per-file metadata, retry/language/timeout metadata, and the rule that no canonical partial output is installed after a job failure or parent cancellation.
8. Update internal/stage/transcribe_test.go to protect the refactored outcomes:
   • configured concurrency remains the observed maximum and never exceeds the configured limit;
   • a speaker failure is returned with speaker context and cancels/blockades remaining work without deadlock;
   • invalid JSON and authoritative-output mismatch remain speaker-qualified;
   • parent cancellation wraps context.Canceled, reports completed/planned context, and installs no partial canonical output;
   • an already-canceled context makes no WhisperX request; and
   • successful results and metadata remain deterministic by speaker. Use synchronization channels rather than timing alone where a new failure- cancellation test needs ordering.
9. Update docs/internal/stage-transcribe.md to describe bounded per-job errgroup execution and all-or-nothing canonical materialization. Keep docs/integrations/whisperx.md implementation-neutral unless a retained integration contract actually changed.

Exit Criteria

• transcribe.go contains no manual worker channel, worker goroutine loop, shared first-error slot, or manual stage-cancel function.
• go.mod records golang.org/x/sync v0.22.0 directly and GOWORK=off go mod tidy -diff succeeds.
• go test ./internal/stage -run '^TestTranscribeStage' and go test -race ./internal/stage -run '^TestTranscribeStage' pass repeatedly, including with -shuffle=on -count=10.
• go test ./..., go test -race ./..., go vet ./..., go build ./..., and git diff --check succeed.

Stage 6 — Integrated Validation And Workstream Closure

Status: Pending

Goal

Verify the combined baseline, process, adapter-file, and transcription changes at every maintained repository boundary and close only this workstream.

Required Work

1. Review the complete Workstream 1 diff against this plan and refactoring.md. Remove obsolete imports, helpers, comments, tests, and documentation claims introduced solely by the replaced mechanisms. Do not opportunistically implement Workstream 2 filesystem simplification or external subprocess-library extraction.
2. Confirm canonical documentation is current:
   • docs/development.md and docs/release.md identify Go 1.26;
   • docs/internal/adapters.md describes the internal mechanism/policy split and retained process-tree semantics;
   • docs/internal/stage-transcribe.md describes bounded per-job execution, cancellation, deterministic ordering, and all-or-nothing canonical materialization; and
   • integration documents retain accurate external contracts without exposing unnecessary private implementation detail.
3. Search maintained code and configuration for stale Go 1.25 build-image or baseline assertions, PID-based Windows process reopening, removed subprocess writer calls, and the old transcription worker machinery. Exclude historical audit descriptions and unrelated numeric values from mechanical rewrites.
4. Run the complete release-candidate-equivalent local validation with Go 1.26:
   • GOWORK=off go mod tidy -diff;
   • gofmt -l across tracked Go files, requiring no output;
   • git diff --check and git diff --cached --check;
   • go test -count=1 ./...;
   • go test -race -count=1 ./...;
   • go vet ./...;
   • go build ./...;
   • go test -count=1 ./internal/doccheck;
   • go test -count=1 ./internal/config -run '^TestExamplesLoadAndValidate$'; and
   • scripts/build-release-assets.sh with a valid synthetic version and a fresh absolute temporary output directory, proving all six official CGO-disabled targets compile and the host smoke binary reports that version.
5. Run the scheduled-CI stress command go test -race -shuffle=on -count=3 ./.... If a failure is genuinely flaky, diagnose and correct the retained concurrency contract; do not weaken or skip the test to close the stage.
6. After every check succeeds, change only Workstream 1's status in docs/roadmap/refactoring.md from Pending to Complete. Leave all later workstreams pending and leave historical audit decisions intact. Update the status of all six stages in this document to Completed as implementation history.

Exit Criteria

• All commands above succeed from a clean, Go 1.26 repository checkout.
• Linux/macOS native-host evidence and Windows/macOS cross-build evidence are reported accurately; no unrun native platform test is claimed.
• No API key value appears in generated files, diagnostics, errors, fixtures, or the diff.
• Workstream 1's consolidated target state is fully implemented, its status is Complete, every later workstream remains Pending, and the worktree is clean after the implementation-stage commit.

Open Questions

None. The audits, refactoring roadmap, approved Go 1.26 revision, and decisions above resolve the product, compatibility, dependency, ownership, testing, and platform choices required to implement this workstream.