… and test isolation

Combined response to inline review on PR #260, kept as one commit because
the test changes are tightly coupled to the production refactor.

Production:
- Route the global Claude Code fallback through Global.Path.home so
  OPENCODE_TEST_HOME (the codebase's existing test isolation pattern,
  see packages/shared/src/global.ts:24) makes the fallback deterministic
  in tests; os.homedir() is locked at process start in Bun.
- Expand InstructionSource union with a 'considered' variant so the
  diagnostic can report candidates that were checked but skipped by
  priority or absent (issue #230 acceptance #7 says 'considered, loaded,
  ignored', not just two states).
- Rewrite sources() to walk project files, the full global priority
  chain, config.instructions URLs, and the explicitly ignored Claude
  Code fallback. Closes the gap where sources() under-reported what
  system() actually loads (URLs were missing).
- Surface OPENCODE_DISABLE_CLAUDE_CODE_PROMPT as a separate ignore
  reason so opencode CLI users with that flag set also get a clear
  diagnostic.

Tests:
- Replace the brittle os.homedir() guard in the ignored-Claude test with
  OPENCODE_TEST_HOME + a tmpdir, removing the CI-environment-dependent
  early return CodeRabbit flagged.
- Add OPENCODE_TEST_HOME to the env capture/restore block.
- Add a regression test for the non-PawWork branch of the gate so an
  accidental inversion or future Runtime.isPawWork() change is caught.
- Add tests covering the new considered (priority-skipped global) and
  URL diagnostic entries.

Adds Instruction.sources() returning structured InstructionSource entries
so debug surfaces can explain which files the system loaded, which were
considered but skipped or absent, and which were intentionally ignored
(issue #230, acceptance #7).

The diagnostic walks the same logical sources system() does so prompt
and trace stay in lockstep:

- Project AGENTS.md / CLAUDE.md / CONTEXT.md priority chain.
- Full global priority chain (PAWWORK_CONFIG_DIR / OPENCODE_CONFIG_DIR /
  Global.Path.config) with first-existing as loaded and subsequent
  existing entries as considered with a priority-skipped reason; absent
  entries are considered with reason 'absent'.
- Local file entries from config.instructions, glob-resolved exactly as
  systemPaths() does (lines 159-174), reported as loaded or considered
  when the spec resolves to no files.
- Remote URL entries from config.instructions, reported as loaded on
  successful fetch and considered with reason on failure.
- Explicitly ignored ~/.claude/CLAUDE.md, with reason set to either the
  PawWork product baseline (Runtime.isPawWork()) or
  OPENCODE_DISABLE_CLAUDE_CODE_PROMPT depending on which gate suppressed
  it. Skipped when the path is already in loadedPaths to avoid double
  reporting.

Tests cover loaded project AGENTS.md, the priority-skipped global
considered branch, both URL outcomes via OPENCODE_CONFIG_CONTENT, the
local file path branch via PAWWORK_CONFIG_DIR + OPENCODE_DISABLE_PROJECT_CONFIG,
and the ignored Claude Code fallback with reason. All home-directory
isolation runs through OPENCODE_TEST_HOME so Bun's locked os.homedir()
doesn't leak the user's real home into the assertions.

Adds Instruction.sources() returning structured InstructionSource entries
so debug surfaces can explain which files the system loaded, which were
considered but skipped or absent, and which were intentionally ignored
(issue #230, acceptance #7).

The diagnostic walks the same logical sources system() does so prompt
and trace stay in lockstep:

- Project AGENTS.md / CLAUDE.md / CONTEXT.md priority chain.
- Full global priority chain (PAWWORK_CONFIG_DIR / OPENCODE_CONFIG_DIR /
  Global.Path.config) with first-existing as loaded and subsequent
  existing entries as considered with a priority-skipped reason; absent
  entries are considered with reason 'absent'.
- Local file entries from config.instructions, glob-resolved exactly as
  systemPaths() does (lines 159-174), reported as loaded or considered
  when the spec resolves to no files.
- Remote URL entries from config.instructions, reported as loaded on
  successful fetch and considered with reason on failure.
- Explicitly ignored ~/.claude/CLAUDE.md, with reason set to either the
  PawWork product baseline (Runtime.isPawWork()) or
  OPENCODE_DISABLE_CLAUDE_CODE_PROMPT depending on which gate suppressed
  it. Skipped when the path is already in loadedPaths to avoid double
  reporting.

Tests cover loaded project AGENTS.md, the priority-skipped global
considered branch, both URL outcomes via OPENCODE_CONFIG_CONTENT, the
local file path branch via PAWWORK_CONFIG_DIR + OPENCODE_DISABLE_PROJECT_CONFIG,
and the ignored Claude Code fallback with reason. All home-directory
isolation runs through OPENCODE_TEST_HOME so Bun's locked os.homedir()
doesn't leak the user's real home into the assertions.

Adds Instruction.sources() returning structured InstructionSource entries
so debug surfaces can explain which files the system loaded, which were
considered but skipped or absent, and which were intentionally ignored
(issue #230, acceptance #7).

The diagnostic walks the same logical sources system() does so prompt
and trace stay in lockstep:

- Project AGENTS.md / CLAUDE.md / CONTEXT.md priority chain.
- Full global priority chain (PAWWORK_CONFIG_DIR / OPENCODE_CONFIG_DIR /
  Global.Path.config) with first-existing as loaded and subsequent
  existing entries as considered with a priority-skipped reason; absent
  entries are considered with reason 'absent'.
- Local file entries from config.instructions, glob-resolved exactly as
  systemPaths() does (lines 159-174), reported as loaded or considered
  when the spec resolves to no files.
- Remote URL entries from config.instructions, reported as loaded on
  successful fetch and considered with reason on failure.
- Explicitly ignored ~/.claude/CLAUDE.md, with reason set to either the
  PawWork product baseline (Runtime.isPawWork()) or
  OPENCODE_DISABLE_CLAUDE_CODE_PROMPT depending on which gate suppressed
  it. Skipped when the path is already in loadedPaths to avoid double
  reporting.

Tests cover loaded project AGENTS.md, the priority-skipped global
considered branch, both URL outcomes via OPENCODE_CONFIG_CONTENT, the
local file path branch via PAWWORK_CONFIG_DIR + OPENCODE_DISABLE_PROJECT_CONFIG,
and the ignored Claude Code fallback with reason. All home-directory
isolation runs through OPENCODE_TEST_HOME so Bun's locked os.homedir()
doesn't leak the user's real home into the assertions.

…nd ignored chains

Adds Instruction.sources() returning structured InstructionSource entries
so debug surfaces can explain which files the system loaded, which were
considered but skipped or absent, and which were intentionally ignored
(issue #230, acceptance #7). This commit covers the project priority
chain, the global priority chain, and the explicitly ignored
~/.claude/CLAUDE.md; config.instructions handling lands in a follow-up.

Marks a file as loaded only after read() returns non-empty content so
diagnostics agree with what system() actually reads into the prompt.
Files whose content reads back empty are downgraded to considered with
reason 'file is empty or unreadable'.

The ignore reason distinguishes Runtime.isPawWork() (PawWork product
baseline) from OPENCODE_DISABLE_CLAUDE_CODE_PROMPT (legacy opencode CLI
opt-out), and dedupes against loadedPaths so a file never appears as
both loaded and ignored.

Tests cover loaded project AGENTS.md, the priority-skipped global
considered branch, the project priority chain (AGENTS.md + CLAUDE.md),
the empty-file downgrade, and the ignored Claude Code fallback with
reason. All home-directory isolation runs through OPENCODE_TEST_HOME.